Exhibit 12.1

Ameren Corporation

Computation of Ratio of Earnings to Fixed Charges

(Thousands of Dollars, Except Ratios)



|                                                                         |  |                                 |         |   |                                        |   |           |  
|------------------------------------------------------------------------ |  | ------------------------------- | ------- | - | -------------------------------------- | - | --------- | -
|                                                                         |  | Three Months EndedMarch 31,2009 |         |   | Year
Ended      December 31,      2008 |  
|Net income from continuing operations attributable to Ameren Corporation |  | $                               | 141,288 |   |                                        | $ | 605,189   |  
|Less - Net income attributable to noncontrolling interest                |  |                                 | (1,826  | ) |                                        |   | (28,422   | )
|Add- Taxes based on income                                               |  |                                 | 69,628  |   |                                        |   | 326,736   |  
|                                                                         |  |                                 |         |   |                                        |   |           |  
|Net income before income taxes and noncontrolling interest               |  |                                 | 212,742 |   |                                        |   | 960,347   |  
|Add- fixed charges:                                                      |  |                                 |         |   |                                        |   |           |  
|Interest on long term debt(1)                                            |  |                                 | 118,500 |   |                                        |   | 440,507   |  
|Estimated interest cost within rental expense                            |  |                                 | 1,873   |   |                                        |   | 6,510     |  
|Amortization of net debt premium, discount, and expenses                 |  |                                 | 3,944   |   |                                        |   | 19,716    |  
|Subsidiary preferred stock dividends                                     |  |                                 | 2,469   |   |                                        |   | 10,357    |  
|Adjust preferred stock dividends to pretax basis                         |  |                                 | 1,196   |   |                                        |   | 5,497     |  
|                                                                         |  |                                 |         |   |                                        |   |           |  
|Total fixed charges                                                      |  |                                 | 127,982 |   |                                        |   | 482,587   |  
|                                                                         |  |                                 |         |   |                                        |   |           |  
|Less: Adjustment of preferred stock dividends to pretax basis            |  |                                 | 1,196   |   |                                        |   | 5,497     |  
|                                                                         |  |                                 |         |   |                                        |   |           |  
|Earnings available for fixed charges                                     |  | $                               | 339,528 |   |                                        | $ | 1,437,437 |  
|                                                                         |  |                                 |         |   |                                        |   |           |  
|Ratio of earnings to fixed charges                                       |  |                                 | 2.65    |   |                                        |   | 2.97      |  
|                                                                         |  |                                 |         |   |                                        |   |           |  



|(1) | Includes FIN 48 interest expense
|--- | --------------------------------