**EXHIBIT 12.1**

**ABGENIX, INC.**

**COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES**

| ** **                                   | ** **                            | **Year Ended December 31,** | ** ** |
|----------------------------------------------|---------------------------------------|--------------------------------------------|------------|
| ** **                                   | ** **                            | **2005**                                   | ** ** | **2004** | ** ** | **2003** | ** ** | **2002** | ** ** | **2001** | ** ** |
| ** **                                   | ** **                            | **(in thousands)**                    | ** ** |
| Earnings:                                    | ** **                            | ** **                                 | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** |
| Loss before income tax expense               |                                  | $                                          | (206,955   | ) | $ | (187,478 | ) | $ | (196,345 | ) | $ | (208,898 | ) | $ | (60,856 | ) |
| Add:                                         | Fixed charges                         |                                       | 22,796     |   | 15,952 |   | 15,447 |   | 13,556 |   | 4,678 |   |
|                                         | Amortization of  capitalized interest |                                       | 162        |   | 163 |   | 99 |   | 1 |   | — |   |
| Less:                                        | Capitalized  interest                 |                                       | (1,070     | ) | (1,687 | ) | (2,470 | ) | (1,924 | ) | — |   |
|                                         |                                  | $                                          | (185,067   | ) | $ | (173,050 | ) | $ | (183,269 | ) | $ | (197,265 | ) | $ | (56,178 | ) |
| Fixed charges:                               | ** **                            | ** **                                 | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** | ** ** |
| Interest expense                             |                                  | $                                          | 15,205     |   | $ | 7,233 |   | $ | 5,784 |   | $ | 4,830 |   | $ | 259 |   |
| Capitalized interest                         |                                  | 1,070                                      |       | 1,687 |   | 2,470 |   | 1,924 |   | — |   |
| Estimated interest portion of rental expense |                                  | 6,521                                      |       | 7,032 |   | 7,193 |   | 6,802 |   | 4,419 |   |
|                                         |                                  | $                                          | 22,796     |   | $ | 15,952 |   | $ | 15,447 |   | $ | 13,556 |   | $ | 4,678 |   |
| Deficiency of earnings to fixed charges      |                                  | $                                          | (207,863   | ) | $ | (189,002 | ) | $ | (198,716 | ) | $ | (210,821 | ) | $ | (60,856 | ) |
| Ratio of earnings  to fixed charges          |                                  | —                                     |       | — |   | — |   | — |   | — |   |

 

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