World Health Organisation guidelines recommend nevirapine 2 mg/kg/d for HIV-exposed infants <2 kg, but 4-6 mg/kg/d for infants >2 kg. In 116 low birth weight infants, nevirapine 2 mg/kg/d until 14 days, and 4 mg/kg/d thereafter, was safe (1 mild possibly related rash) and achieved target plasma concentrations. Concentrations decreased with treatment duration. Routine dose increase at 14 days should be considered.