Abstract: Objective To evaluate bioequivalence of two specifications of ubenimex capsules in comparison with the Japanese branded product (R). Methods The study adopted a 3-way crossover design in twenty-four healthy male volunteers, whose plasma concentrations of ubenimex were determined by UPLC-MS/MS after administration a single oral dose of 30 mg of domestic ubenimex T1 (10 mg/capsule), T2 (30 mg/capsule) and branded ubenimex R (30 mg/capsule) sequentially. The bioequivalence was evaluated using WinNonlin6.1 statistical analysis software. Results One volunteer was excluded because of failure to follow medication instructions. The main pharmacokinetic parameters of ubenimex of T1, T2 and R were as follows: Cmax(2 646.73±454.09) ng/mL,(2 675.91±474.32)ng/mL and(2 432.79±544.32) ng/mL, respectively;Tmax(0.68±0.23) h,(0.76±0.19) h and (0.77±0.26) h,respectively;AUC0-t(3 925.23±478.34)(ng·h)/mL, (3 804.62±448.84)(ng·h)/mL and (3 789.30±443.15)(ng·h)/mL, respectively;AUC0-∞(3 938.31±479.54)(ng·h)/mL,(3 817.26±450.90)(ng·h)/mL and (3 800.90±444.77) (ng·h)/mL, respectively;CL/F(7.72±0.92) L/h, (7.97±0.98) L/h and (7.99±0.90) L/h, respectively;Vd(26.08±9.20)L,(25.65±10.22) L and (26.03±10.05) L, respectively. The relative bioavailability F0-tand F0-∞of T1 and T2 against the branded preparation R were (103.90±9.19)% and (100.77±9.36)%, and (103.93±9.20)% and (100.79±9.33)%, respectively. Conclusion Both ubenimex capsules T1 and T2 are bioequivalent to the Japanese branded products．