A pharmacokinetic study of ampicillin (6 mg/kg intravenous) revealed that the peak concentrations of 17.81 +/- 1.25, 5.64 +/- 2.24 and 1.09 +/- 0.10 micrograms/ml of the drug were attained at 15 min, 30 min and 2 h in plasma, milk and uterine fluid respectively. A therapeutic concentration of greater than or equal to 0.1 microgram/ml was maintained from 15 min-8 h, 15 min-6 h and 30 min-6 h in plasma, milk and uterine fluid. Hence, the drug may be used effectively in mammary gland and uterine infections apart from its use in other systemic infections.