The pharmacokinetics of clindamycin and gentamicin were studied in women given these antibiotics prior to cesarean section. Maternal clindamycin levels were within the normal range and cord levels were within the therapeutic range for this antibiotic. For gentamicin, however, maternal levels were depressed, with a concurrent depression of cord levels. This may have significant implications for the use of gentamicin in maternal and fetomaternal infections.