<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
                                                       March 31, 1999             December 31, 1998         December 31, 1997
                                                     -------------------        -------------------       -------------------

EARNINGS AS DEFINED (1)
<S>                                                         <C>                      <C>                       <C>     
Net Income................................................  $146,502                 $114,619                  $125,630
Fixed charges.............................................    59,622                   61,304                    57,905
                                                            --------                 --------                  --------
  Earnings as defined.....................................  $206,124                 $175,923                  $183,535
                                                            ========                 ========                  ========
                                                                                                                       
FIXED CHARGES AS DEFINED (1)                                                                                           
Interest on long-term debt................................  $ 46,021                 $ 47,091                  $ 47,024
Interest on other borrowed funds..........................    11,511                   12,113                     8,664
Amortization of debt discounts, premium                                                                                
  and expense.............................................       929                      955                     1,032
Interest implicit in rentals (2)..........................     1,161                    1,145                     1,185
                                                            --------                 --------                  --------
  Fixed charges as defined................................  $ 59,622                 $ 61,304                  $ 57,905
                                                            ========                 ========                  ========
                                                                                                                       
                                                                                                                       
Ratio of Earnings to Fixed Charges..............................3.46                     2.87                      3.17
                                                                ====                     ====                      ====
</TABLE>

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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.