Objective To investigate the chemical constituents of marine sponge A gelas mauritiana collected from the South China Sea .Methods The n-butanol extract of marine sponge A gelas mauritiana was separated and purified by repeated column chromatography on silica gel ,Sephadex LH-20 ,and reversed-phase high-performance liquid chromatography (RP-HPLC) .The chemical structures of those obtained compounds were determined on the basis of spectroscopic analysis and com-parison with reported data .The tumor cell growth inhibitory activity of these compounds towards human lung carcinoma cells A549 was tested .Results Eight compounds were isolated ,including agelasine A (1) ,agelasine B (2) ,epi-agelasine C (3) , (-)agelasine D (4) ,agelasine E (5) ,agelasine F (6) ,(-)ageloxime D (7) and aurantiamide acetate (8) .These compounds dis-played different level of tumor cell growth inhibitory activity towards cell A 549 in vitro .Compounds 1-3 showed significant ac-tivity towards cell A549 ,being similar to that of the positive control of adriamycin .Conclusion Compounds 1 ,2 ,4 ,5 ,6 ,8 were isolated for the first time from the sponge A gelas mauritiana .Cell A549 was selected for the first time for the activity evalua-tion of compounds 1~7 .Significant inhibition activity of compounds 2、3 may hold as a basis for further research .