Objective: To compare the prepartum and postpartum feasibility and acceptance of voluntary counseling and rapid testing (VCT) among women with unknown HIV status in South Africa. Methods: Eligible women were randomized according to the calendar week of presentation to receive VCT either while in labor or after delivery. Results: Of 7238 women approached, 542 (7.5%) were eligible, 343 (63%) were enrolled, and 45 (13%) were found to be HIV infected. The proportions of eligible women who accepted VCT were 66.8% (161 of 241) in the intrapartum arm and 60.5% (182 of 301) in the postpartum arm, and the difference of 6.3% (95% CI, - 1.8% to 14.5%) was not significant. The median times (44 and 45 minutes) required to conduct VCT were also similar in the 2 arms. In the intrapartum arm, all women in true labor received their test results before delivery and all those found to be HIV positive accepted prophylaxis with nevirapine before delivery. Conclusions: Rapid testing in labor wards for women with an unknown HIV status is feasible and well accepted, and allows for a more timely antiretroviral prophylaxis than postpartum testing. © 2010 International Federation of Gynecology and Obstetrics.