Ampicillin and clindamycin were once administered in rabbits via oral and i.v. routes in doses of 25 andl6 mg/kg b.wt., respectively, to determine blood concentration, kinetic behaviour and bioavailability. Following a single i.v. injection, the blood concentration-time curve indicated a two compartment open model, with an climination half-life value (to.5, (B),) of 103.03 and 209.41 minutes for ampicillin and clindamycin, respectively. The apparent volume of distribution of ampicillin in rabbits was less than 1 litre/kg and suggesting a lower distribution in tissues than in blood. While, the apparent volume of distribution of clindamycin in rabbits was more than 1 litre/kg and suggesting a higher distribution in tissues than in blood. After oral administration the peak plasma concentration of ampicillin and clindamycin were 11.03 and 2.25ug/ml at 2.45 and 0.96 hours, respectively. The average bioavailability of ampicillin and clindamycin given by oral administration, were 0.44 and 0.56%, respectively.