Three alkaloids were isolated from the leaves of Pilea martinii (H.Lév) Hand-Mazz. Theirs structures were established by spectroscopic analysis including MS and NMR. Accordingly, the isolates were identified as 1,3,6,6-tetramethyl-5,6,7,8-tetrahydroisoquinolin-8-one (1), julandine (2), cryptopleurine (3). Compound 2 and 3 have shown potent cytotoxicity against four human tumor cell lines (KB, HepG2, MCF-7 and LU-1) with IC50 values of 0.07-0.26 µg/ml.
