Abstract: OBJECTIVE To study the aspirin sustained release based on the matrix of mesoporous molecular sieve MCM-41. METHODS Mesoporous molecular sieve MCM-41 was synthesized using TEOS as silicon source and CTAB as templates at room temperature and under acidic conditions. Aspirin was loaded into MCM-41 by immersion method. The obtained aspirin-MCM-41 assembly was characterized by IR, XRD and N₂-adsorption method. The maximum aspirin loading was determined. Finally the extended release of aspirin in assembly was demonstrated by in vitro release study. RESULTS The maximum aspirin loading into MCM-41 was 0.34 g·g^-1. 67.6% and 90.2% of aspirin was released from the assembly at 8 h and 31 h, respectively. CONCLUSION The result showed that the effect of slow release for aspirin was achieved by using the mesoporous molecular sieve MCM-41 as matrix, indicating a potential application of mesoporous molecular sieve in the sustained drug release system.