Abstract: In order to avoid high initial peak of the commercially available indomethacin formulation and increase the interval between dosages, comparison of three sustained release indomethacin capsules on pellet coated with Eudragit-E₃₀D and a commercially available tablet was carried out by testing in vitro the dissolution behaviour and in vivo bioavailability. Dissolution studies on three batches of pellet capsules with varying drug to coat material ratios (mg/cm²) exhibited a sustained release pattern. In vivo serum level for 8 adult male subjects of randomized crossover design showed no statistical difference in bioavailability between different capsule formulations and a tablet formulation available on the market. However, these three capsule formulations demonstrated a higher and smoother serum concentrationtime curves than that of the tablet formulation from 4 to 12 h following a single dose(50mg). The serum level of three capsule formulations was significantly higher than that of the tablet formulation (P<0.1) at the 12th h respectively. In vitro dissolution behaviour and in vivo bioavailability, the linear relationships were found between T₅₀ or T_max and drug to coat material ratios.