EIGHTH AMENDMENT TO CREDIT AGREEMENT

EXHIBIT 4.1

EIGHTH AMENDMENT TO CREDIT AGREEMENT

     EIGHTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 10, 2005, among AMERISTAR CASINOS, INC., a Nevada corporation (the “Borrower”), the various lenders party to the Credit Agreement referred to below (the “Lenders”) and DEUTSCHE BANK TRUST COMPANY AMERICAS (f/k/a Bankers Trust Company), as Administrative Agent (all capitalized terms used herein and not otherwise defined herein shall have the respective meanings provided such terms in the Credit Agreement as defined below).

W I T N E S S E T H:

     WHEREAS, the Borrower, the Lenders, the Administrative Agent and the other agents party thereto are party to a Credit Agreement, dated as of December 20, 2000, as subsequently amended, modified or supplemented by the First Amendment thereto dated as of January 30, 2001, the Second Amendment thereto dated as of May 31, 2002, the Third Amendment thereto dated as of November 22, 2002, the Fourth Amendment thereto dated as of December 19, 2003, the Fifth Amendment thereto dated as of February 27, 2004, the Sixth Amendment thereto dated as of October 25, 2004 and the Seventh Amendment thereto dated as of December 21, 2004 (the “Credit Agreement”);

     WHEREAS, the Borrower has requested that the Lenders agree to certain amendments to the Credit Agreement; and

     WHEREAS, the Borrower and the Lenders wish to amend the Credit Agreement as provided herein;

     NOW, THEREFORE, it is agreed:

     1. Section 9.03(iii) of the Credit Agreement is hereby amended by (i) deleting the text “$25,000,000” appearing in sub-clause (x)(I) of said Section and inserting the text “$32,500,000” in lieu thereof.

     2. The Borrower hereby represents and warrants that (i) no Default or Event of Default exists as of the Eighth Amendment Effective Date (as defined below) both before and after giving effect to this Amendment and (ii) on the Eighth Amendment Effective Date, both before and after giving effect to this Amendment, all representations and warranties (other than those representations made as of a specified date) contained in the Credit Agreement and in the other Credit Documents are true and correct in all material respects.

     3. This Amendment shall become effective on the date (the “Eighth Amendment Effective Date”) when the Required Lenders and the Borrower shall have signed a counterpart hereof (whether the same or different counterparts) and shall have delivered (including by way of facsimile transmission) the same to the Administrative Agent at White & Case LLP, ▇▇▇▇ ▇▇▇▇▇▇ ▇▇ ▇▇▇ ▇▇▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention: May ▇▇▇-▇▇▇▇▇▇▇ (facsimile number 212-354-8113).

     4. This Amendment is limited as specified and shall not constitute a modification, acceptance or waiver of any other provision of the Credit Agreement or any other Credit Document.

     5. This Amendment may be executed in any number of counterparts and by the different parties hereto on separate counterparts, each of which counterparts when executed and delivered shall be an original, but all of which shall together constitute one and the same instrument. A complete set of counterparts shall be lodged with the Borrower and the Administrative Agent.

     6. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

*          *          *

     IN WITNESS WHEREOF, the parties hereto have caused their duly authorized officers to execute and deliver this Amendment as of the date first above written.

		SENIOR DEBT PORTFOLIO
				By:		Boston Management and Research as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ SENIOR INCOME TRUST
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ INSTITUTIONAL SENIOR LOAN FUND
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ CDO III, LTD.
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		COSTANTINUS ▇▇▇▇▇ ▇▇▇▇▇ CDO V, LTD.
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ CDO VI, LTD.
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President

		▇▇▇▇▇▇▇ & CO
				By:		Boston Management and Research as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		THE NORINCHUKIN BANK, NEW YORK BRANCH, through State Street Bank and Trust Company N.A. as Fiduciary Custodian
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management, Attorney-in-fact
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		BIG SKY III SENIOR LOAN TRUST
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ VT FLOATING-RATE INCOME FUND
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ LIMITED DURATION INCOME FUND
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		TOLLI & CO.
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President

		▇▇▇▇▇ ▇▇▇▇▇ SENIOR FLOATING-RATE TRUST
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President
		▇▇▇▇▇ ▇▇▇▇▇ FLOATING-RATE INCOME TRUST
				By:		▇▇▇▇▇ ▇▇▇▇▇ Management as Investment Advisor
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Vice President

		ML CLO XX PILGRIM AMERICA (CAYMAN) LTD.
				By:		ING Investments LLC as its Investments Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Senior Vice President
		ING SENIOR INCOME FUND
				By:		ING Investment Management, Co. as its Investments Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Senior Vice President
		ING PRIME RATE TRUST
				By:		ING Investment Management, Co. as its Investments Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Senior Vice President
		ARCHIMEDES FUNDING III, LTD.
				By:		ING Capital Advisors LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
				Title: Director
		ARCHIMEDES FUNDING IV (CAYMAN), LTD.
				By:		ING Capital Advisors LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
				Title: Director
		ENDURANCE CLO I, LTD.
				By:		ING Capital Advisors LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
				Title: Director
		NEMEAN CLO, LTD.
				By:		ING Capital Advisors LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
				Title: Director
		SEQUILS-ING I (HBDGM), LTD.
				By:		ING Capital Advisors LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
				Title: Director

		LCM I LIMITED PARTNERSHIP
				By:		Lyon Capital Management LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇
				Title: Portfolio Manager
		LCM II LIMITED PARTNERSHIP
				By:		Lyon Capital Management LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇
				Title: Portfolio Manager
		LCM III LTD.
				By:		Lyon Capital Management LLC, as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇
				Title: Portfolio Manager
		LONGHORN CDO (CAYMAN) LTD.
				By:		▇▇▇▇▇▇▇ ▇▇▇▇▇ Investment Managers, L.P. as its Investments Manager
		By:		/s/ ▇▇▇▇▇▇ ▇▇▇▇▇
				Title: Authorized Signatory
		MASTER SENIOR FLOATING RATE TRUST
		By:		/s/ ▇▇▇▇▇▇ ▇▇▇▇▇
				Title: Authorized Signatory
		NATIONAL CITY BANK OF INDIANA
		By:		/s/ ▇▇▇▇ ▇▇▇▇▇▇
				Title: Vice President
		CENTURION CDO II, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations

		SEQUILS-CENTURION V, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		CENTURION CDO VI, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		CENTURION CDO VII, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		CENTURION CDO 8, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		CENTURION CDO 9, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		CENTURION CDO III, LTD.
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇
				Title: Director – Operations
		IDS LIFE INSURANCE COMPANY
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Senior Managing Director

		AMERIPRISE CERTIFICATE COMPANY
				By:		RiverSource Investments, LLC as Collateral Manager
		By:		/s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
				Title: Senior Managing Director