The study was conducted to investigate the pharmacokinetics and relative bioavailability of clindamycin after administration of two oral clindamycin HCl formulations. A new tablet preparation containing 600 mg clindamycin (Clinda-saar 600, test) was compared to a marketed capsule containing 300 mg clindamycin (Sobelin 300, reference). Both preparations revealed comparable in vitro dissolution profiles with high batch conformity and homogeneity. Twenty healthy male volunteers received single doses of 600 mg clindamycin (test: 1 tablet, reference: 2 capsules) in an open, randomized, two-period crossover design. Blood samples were drawn up to 14 h p.a. and clindamycin plasma concentrations were measured using a sensitive and specific HPLC-UV method. Pharmacokinetic characteristics were similar for both preparations, arithmetic mean values (standard deviation) were computed as: AUC(0-infinity) 12.2 (4.2) and 13.1 (4.6) microg x h/ml, Cmax 3.1 (0.8) and 3.4 (0.8) microg/ml, t(max) 0.83 (0.24) and 0.85 (0.34) h, t(1/2) 2.3 (0.4) and 2.3 (0.6) h for test and reference, respectively. Mean relative bioavailability (point estimate) was 93% for AUC and 91% for Cmax. 90% confidence intervals for AUC and Cmax were within the predefined bioequivalence acceptance limits. Bioequivalence of test and reference preparations could be demonstrated. Single doses of 600 mg clindamycin orally were well tolerated without relevant differences between both preparations.