With funds from Elizabeth Glaser Pediatric AIDS Foundation, the Cameroon Baptist Convention Health Board implemented a program to prevent mother-to-child transmission of HIV-1 (PMTCT) as part of its routine antenatal care, with single-dose maternal and infant peripartum nevirapine (NVP) prophylaxis of HIV-positive mothers and their babies. Nurses, midwives, nurse aides, and trained birth attendants counseled pregnant women, obtained risk factor data, and offered free HIV testing with same-day results. From February 2000 through December 2004, this program rapidly expanded to 115 facilities in 6 of Cameroon's 10 provinces, not only to large hospitals but to remote health centers staffed by trained birth attendants. We trained 690 health workers in PMTCT and counseled 68,635 women, 91.9% of whom accepted HIV testing. Of 63,094 women tested, 8.7% were HIV-1-positive. Independent risk factors for HIV-1 infection included young age at first sexual intercourse, multiple sex partners, and positive syphilis serology (P < 0.001 for each). We counseled 98.7% of positive and negative mothers on a posttest basis. Of 5550 HIV-positive mothers, we counseled 5433 (97.9%) on single-dose NVP prophylaxis. Consistent training and programmatic support contributed to rapid upscaling and high uptake and counseling rates.