<PAGE>   1
                                                                    EXHIBIT 12-1


              MICHIGAN CONSOLIDATED GAS COMPANY AND SUBSIDIARIES
              COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
                            (THOUSANDS OF DOLLARS)



<TABLE>
<CAPTION>
                                                     Twelve Months Ended  Twelve Months Ended  Twelve Months Ended     
                                                     -------------------  -------------------  -------------------     
                                                           June 30, 1997   December 31, 1996    December 31, 1995      
                                                     -------------------  -------------------  -------------------     
<S>                                                  <C>                  <C>                  <C>                     
                                                                                                                       
EARNINGS AS DEFINED (1)                       
Net Income  ..................................             $109,406              $122,239             $112,727         
Fixed charges  ...............................               57,100                53,831               45,637         
                                                           --------              --------             --------         
 Earnings as defined  ........................             $166,506              $176,070             $158,364         
                                                           ========              ========             ========         
                                              
FIXED CHARGES AS DEFINED (1)                  
Interest on long-term debt  ..................             $ 45,546              $ 43,163              $35,820     
Interest on other borrowed funds  ............                8,986                 8,012                7,053     
Amortization of debt discounts, premium       
 and expense  ................................                1,085                 1,081                  996     
Interest implicit in rentals (2)  ............                1,483                 1,575                1,768     
                                                           --------              --------             --------     
 Fixed charges as defined  ...................             $ 57,100              $ 53,831             $ 45,637     
                                                           ========              ========             ========     
                                              
Ratio of Earnings to Fixed Charges  ..........                 2.92                  3.27                 3.47     
                                                           ========              ========             ========     
</TABLE>                                      
                                                     
                                                    

Notes:
(1)  Earnings and fixed charges are defined and computed in accordance with
     Item 503 of Regulation S-K.
(2)  This amount is estimated to be a reasonable approximation of the
     interest portion of rentals.

MichCon is a guarantor of certain other debt.  Fixed charges related to such
debt are deemed to be immaterial and therefore have been excluded from the above
ratios.