One hundred eighty-nine twin pregnancies were delivered at Wilford Hall United States Air Force Medical Center from July 1977 through December 1985. Among these, 57 were referred from distant bases and were excluded from further analysis. The remaining 132 pregnancies from our local population make up the study group. Sixty-seven women (51%) followed our advice to be hospitalized at or before 28 weeks' gestation for prophylactic ward rest. The remaining 65 women (49%) were not hospitalized until after 28 weeks' gestational age or until a pregnancy complication or labor occurred. Only three of 134 infants (2%) whose mothers were admitted died, versus 11 of 130 infants (8.5%) whose mothers were not admitted (P <.03). The results suggest that prophylactic ward rest, implemented at or before 28 weeks' gestational age, may reduce perinatal mortality in this condition. © 1987 by The American College of Obstetricians and Gynecologists.