<PAGE>   1
                                                                      Exhibit 12
                     COLUMBIA ENERGY GROUP AND SUBSIDIARIES
                Statements of Ratio of Earnings to Fixed Charges
                                 ($ in millions)

<TABLE>
<CAPTION>
                                                           Twelve Months                          Twelve Months
                                                          Ended September 30,                   Ended December 31,
                                                          -------------------    -------------------------------------------------
                                                            1999       1998      1998        1997       1996       1995       1994
                                                            ----       ----      ----        ----       ----       ----       ----
<S>                                                         <C>        <C>        <C>        <C>        <C>       <C>         <C>
Consolidated Income (Loss) from Continuing Operations
before Income Taxes                                         442.5      392.0      435.4      398.3      337.5     (643.0)     392.2

Adjustments:
  Interest during construction                               (3.0)      (2.2)      (2.1)      (3.0)      (1.1)     (20.2)      --
  Distributed (Undistributed) equity income                  (3.0)       2.4       (0.4)       3.6        1.5       (7.9)      (0.9)
  Fixed charges                                             167.2      179.1      164.9      181.6      184.6    1,061.3       33.7
                                                          -------    -------    -------    -------    -------    -------    -------
    Earnings Available                                      603.7      571.3      597.8      580.5      522.5      390.2      425.0
                                                          -------    -------    -------    -------    -------    -------    -------

Fixed Charges:
  Interest on long-term and short-term debt                 146.3      147.3      145.4      145.6      150.8      987.2        0.7
  Other interest                                              3.1       12.9        1.7       15.2       13.5       53.6       14.1
  Portion of rentals representing interest                   17.8       18.9       17.8       20.8       20.3       20.5       18.9
                                                          -------    -------    -------    -------    -------    -------    -------
Total Fixed Charges *, **                                   167.2      179.1      164.9      181.6      184.6    1,061.3       33.7
                                                          -------    -------    -------    -------    -------    -------    -------

Ratio of Earnings to Fixed Charges                           3.61       3.19       3.63       3.20       2.83        N/A (a)  12.61
                                                          =======    =======    =======    =======    =======    =======    =======
</TABLE>



Prior periods amounts for the twelve months ended December 31, 1997, December
31, 1998, and September 30, 1998 have been restated to reflect Columbia Energy
Services Corporation wholesale and trading operations as discontinued
operations.

(a)  To achieve a one-to-one coverage, the Corporation would need an additional
     $671.1 million of earnings for the twelve months ended December 31, 1995.

*    This amount excludes approximately $230 million of interest expense not
     recorded for the twelve months ended December 31, 1994. This amount
     includes interest expense of $982.9 million including the write-off of
     unamortized discounts on debentures recorded in 1995.

**   This amount excludes $8.6 million of interest expense not recorded with
     respect to the registrant's guarantee of LESOP Trust's debentures for the
     twelve months ended December 31, 1994.