First-born twins are at a four-fold risk of acquiring HIV infection if delivered by caesarean section. A female second twin delivered by caesarean section presented at the age of 14 months with features of HIV/AIDS. She died four months later of full blown AIDS. The first twin, a male, who was delivered vaginally, is asymptomatic and negative for HIV-1 at 18 months of age. He is growing normally. Their father died of AIDS a month before the demise of twin two. Discussion focuses on factors influencing perinatal transmission of HIV and strategies available to minimize the risk. Key Words: HIV, transmission, dizygotic twins. [Jnl College of Medicine Vol.8(2) 2003: 27-30]