Aim The relative bioavailability of domestic ibudilast sustained release capsules in healthy volunteers was observed.Methods A single oral dose of 20 mg of imported and domestic ibudilast sustained release capsules and 10 mg of ibudilast raw material was separately given to 12 healthy volunteers in a randomized crossover study. Ibudilast concentration in plasma was determined by HPLC method.Results The Cmax were (54.9?9.7),(60.7?9.1) and (62.2?11.5) ?g?L-1; the tmax were (3.8?0.8),(3.9?0.8) and (1.8?0.3) h;the t1/2(ke) were (1.5?1.4),(12.1?1.0) and (3.5?0.5) h,and the AUC(0～t) were (618.1?57.7),(588.1?66.6) and (233.0?46.4) ?g?h?L-1 in imported capsule group, domestic capsule group and raw material group respectively. The relative bioavailability of domestic sustained release capsules of ibudilast is (95.6?11.0)%. Conclusion The results of statistical analysis demonstrate that the imported and domestic sustained capsules have significant character of significantly sustained release and are bioequivalent.