<ARTICLE>                     5
<LEGEND>
This schedule contains summary financial information extracted from Swift Energy
Managed Pension Assets Partnership 1990-B, Ltd.'s balance sheet and statement of
operations  contained in its Form 10-Q for the quarter  ended March 31, 1998 and
is qualified in its entirety by reference to such financial statements.
</LEGEND>
       
                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                              DEC-31-1998
<PERIOD-END>                                   MAR-31-1998
<CASH>                                         180,683
<SECURITIES>                                   0
<RECEIVABLES>                                  225,918
<ALLOWANCES>                                   0
<INVENTORY>                                    0
<CURRENT-ASSETS>                               412,886
<PP&E>                                         3,919,941
<DEPRECIATION>                                 (3,357,739)
<TOTAL-ASSETS>                                 975,088
<CURRENT-LIABILITIES>                          4,397
<BONDS>                                        0
<PREFERRED-MANDATORY>                          0
<PREFERRED>                                    0
<COMMON>                                       0
<OTHER-SE>                                     970,691
<TOTAL-LIABILITY-AND-EQUITY>                   975,088
<SALES>                                        62,334
<TOTAL-REVENUES>                               64,901
<CGS>                                          0
<TOTAL-COSTS>                                  24,921<F1>
<OTHER-EXPENSES>                               0
<LOSS-PROVISION>                               0
<INTEREST-EXPENSE>                             0
<INCOME-PRETAX>                                26,789
<INCOME-TAX>                                   0
<INCOME-CONTINUING>                            26,789
<DISCONTINUED>                                 0
<EXTRAORDINARY>                                0
<CHANGES>                                      0
<NET-INCOME>                                   26,789
<EPS-PRIMARY>                                  0
<EPS-DILUTED>                                  0
<FN>
<F1>Includes  lease  operating  expenses,  production  taxes  and  depreciation,
depletion and  amortization  expense.  Excludes gene al and  administrative  and
interest expense.
</FN>