• We investigated 24 completed pregnancies of 20 healthy, human immunodeficiency virus (HIV)–seropositive sex partners of 20 seropositive hemophilic men. One woman had recurrent herpes simplex type 2 infection; no woman was known to use illicit drugs or to have other purported cofactors for vertical HIV transmission. For 8 offspring, the mothers learned of their partners' serostatus and received counseling against pregnancy prior to the fifth month of gestation; for 9 offspring (37.5%), the mothers learned of their own seropositivity and received counseling prior to the fifth month. Acquired immunodeficiency syndrome developed in 7 (35%) of 20 fathers, 4 of whom died; HIV-related symptoms developed in 4; severe liver disease developed in 2; and 7 (35%) were in good health. In four mothers (20%) HIV-related symptoms developed. Five offspring were breast-fed for 2 days to more than 3 years, two while the mother was known to be seropositive; four of these were seronegative and healthy, and one was seropositive at 30 months of age and had persistent cervical lymphadenopathy at 48 months of age. Infants were born at term; median birth weight was 2.86 kg. Solely on the basis of serologic studies and symptoms for those with more than 15 months of follow-up, the minimum perinatal transmission rate for this group of women without putative transmission cofactors (drug usage, promiscuity, malnutrition, HIV symptoms) was at least 25%, a rate comparable to that reported for women in other risk groups.