The bioequivalence study of 200-mg generic acyclovir was conducted in healthy males. The reference Zovirax® and the test Zevin® were administered as a single oral dose after an overnight fast in a two-period, crossover design separated by 1 week. Serial blood samples were collected over a period of 24 hours. Plasma acyclovir concentrations were determined by HPLC and the pharmacokinetic parameters were analyzed by non-compartmental analysis. Results: The t1/2 for the test (4.5 ± 2.4 h) and Zovirax® (3.9 ± 2.6 h) were comparable. The analysis of variance was carried out and the median Tmax (1.50 h) for the test was not statistically difference from Zovirax®. The mean (90% Cl) of the AUC0∞ and the Cmax] ratios for (Test/Reference) were 0.95 (0.83 - 1.09) and 0.95 (0.83 - 1.10), respectively. These values fell within the bioequivalence criteria of 0.80 - 1.25, thus it was concluded that Zevin® and Zovirax® were bioequivalence.