External cephalic version under tocolysis at term was investigated during a prospective study at the Los Angeles County/University of Southern California Medical Center from October 1, 1979 to March 16, 1983. Two hundred twelve patients were considered for attempted version. Forty-one patients were excluded, and 23 patients as previously reported were randomized to the control group. The procedure was successful in 73% (108 of 148). Of the 102 successful versions observed until delivery (six lost to follow-up), 93% (95 of 102) presented in labor with a vertex presentation; seven fetuses reverted to abnormal lies. The cesarean section rate in the success group with a vertex presentation was 24% (23 of 95).