The objective of this study was to compare the bioavailability of new generic product of gabapentin with the innovator’s product. The study was performed in 20 Thai male healthy volunteers who received a single oral dose of 300 mg gabapentin capsule. Double blind randomized two-way crossover design was used with one week washout period between treatments. After drug administration, serial blood sample was collected over a period of 32 hours. Plasma gabapentin was determined by automated high performance liquid chromatography (HPLC) with fluorescence detection after deproteinized with acetonitrile and following derivatization with o-phthalaldehyde (OPA) reagent containing 2-mercaptoethanol. The differences in pharmacokinetic parameters, maximum concentration (Cmax), AUC(0-t) and AUC(0-inf) were analyzed by 2-way analysis of variance (ANOVA) and 90% confidence interval (CI). The values of Cmax of gabapentin were 3.26 ± 0.60 (range of 1.58-4.07) μg/ml and 3.00 ± 0.71 (range of 1.42-3.95) μg/ml for generic and innovator’s products, respectively. The time to peak plasma gabapentin concentration (Tmax, hr) of generic and innovator’s product was 3.08 ± 0.59 (2-4) hours and 3.33 ± 0.63 (2-5) hours, respectively. The area under the plasma concentration-time curve of generic and innovator’s products were 30.06 ± 4.94 vs 27.63 ± 6.45 μg.hr/ml for AUC(0-t) and 30.76 ± 4.88 vs 28.27 ± 6.63 μg.hr/ml for AUC(0-inf), respectively. 90% CI of the difference of log Cmax, log AUC(0-t) and log AUC(0-inf) of generic product compared to innovator’s product were 96.64-124.94%, 97.60-124.43% and 97.90-124.00%, respectively. They were all within the acceptable range of 80-125%, thus we concluded that the two gabapentin formulations were bioequivalent.