Stavudine (5 mg/kg of body weight; n = 7) or didanosine (3.2 mg/kg; n = 4) was administered as an intravenous bolus to pregnant pigtailed macaques (Macaca nemestrina) near term and 4 to 5 weeks postpartum. No significant differences were found between the prenatal and postpartum total plasma drug clearance, steady-state volume of distribution, terminal plasma drug half-life, mean body residence time, or recovery of unchanged drug in urine. These data indicate that pregnancy does not affect the pharmacokinetics of stavudine or didanosine in M. nemestrina.