Two new haemanthamine-type alkaloids, crinasiaticine A (1) and crinasiaticine B (2), along with fifteen known alkaloids 3-17 , were isolated from the bulbs of Crinum asiaticum L. var. asiaticum . The structures of the new compounds were established by spectroscopic analysis and the known compounds were identified by spectral comparison with those previously reported. All of the compounds were evaluated for their inhibitory potential against human carbonic anhydrase isozyme II (hCAII) in vivo activity using a novel yeast-based assay. Compounds 5 and 15 inhibited hCAII activity with minimal effective doses of 166 and 8.7 mu M, respectively. These two compounds did not show cytotoxicity, even at the high concentration used.