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Exhibit 12.1

Abgenix, Inc.
Computation of Ratios of Earnings to Fixed Charges

			Six Months Ended June 30,						Year Ended December 31,
			2005			2004			2004			2003			2002			2001			2000
			(in thousands)
Earnings:
	Loss before income tax expense		$	(126,750	)	$	(102,189	)	$	(187,478	)	$	(196,345	)	$	(208,898	)	$	(60,856	)	$	(8,793	)
	Add:	Fixed charges		11,131			7,636			15,952			15,447			13,556			4,678			1,306
		Amortization of capitalized interest		81			81			163			99			1			—			—
	Less:	Capitalized interest		(538	)		(841	)		(1,687	)		(2,470	)		(1,924	)		—			—
			$	(116,076	)	$	(95,313	)	$	(173,050	)	$	(183,269	)	$	(197,265	)	$	(56,178	)	$	(7,487	)
Fixed charges:
	Interest expense		$	7,067		$	3,290		$	7,233		$	5,784		$	4,830		$	259		$	39
	Capitalized interest			538			841			1,687			2,470			1,924			—			—
	Estimated interest portion of rental expense			3,526			3,505			7,032			7,193			6,802			4,419			1,267
			$	11,131		$	7,636		$	15,952		$	15,447		$	13,556		$	4,678		$	1,306
Deficiency of earnings to fixed charges			$	(127,207	)	$	(102,949	)	$	(189,002	)	$	(198,716	)	$	(210,821	)	$	(60,856	)	$	(8,793	)
Ratio of earnings to fixed charges				—			—			—			—			—			—			—

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Abgenix, Inc. Computation of Ratios of Earnings to Fixed Charges