Sixteen alkaloids have been isolated from the fruits of Kopsia officinalis Tsiang and P. T, Li (Apocynaceae), a plant commonly used in folk medicine for treating tonsillitis and rheumatism. Ten of them were identified as known alkaloids - ebumamenine (l), kopsanone (2), 5, 18-dioxokopsan (3), kopsinilam (4), kopsinine (5), pleiocarpine (6), kopsamine (7), N-carbomethoxy-12-methoxykopsinaline (S), N-carbomethoxy-11, 12-dimethoxykopsinaline (9) and (+)-vincadifformine (13). The other three have now been proved to be new. They are N-carbomethoxy-11-hydroxy-12-methoxykopsinaiine (lo), N-carbomethoxy-11-methoxy-12-hydroxykopsinaline (11) and kopsamine N-oxide (12). More than thirty plants of Kopsia BI. (family Apocynaceae) are known to occur in tropical and subtropical areas of the world. The list of their distribution in China includes K. lancibracteolata Merr., K. fructicosa (Ker.), A. DC., K. hainanensis Tsiang and K. oficinalis Tsiang and P.T. Li.lna Of these four species the latter is native to southern part of YunnaD Province and has long been used in folk medicine for the treatment of tonsillitis, pharyngitis, rheumatism and edema.a Until recently, this plant has been studied chemically of its root, stem bark and lea~es.l*~-~The isolation and structure investigation of chemical constituents in the fruits of K. officinalis are the subject of present work. After decoating and drying, the kernels were ground and extracted by usual means to afford four fractions: A (PH 5), B (pH 6), C (pH 7) and D (pH 9). Fractions B-D were found to be active in the test against lymphocyte carcinoma P-388 cells in vitro. By using column chromatography (CC) and preparative thin-layer chromatography (PTLC), sixteen indole alkaloids were readily isolated. Ten of them (1-9, 13) were identified as known alkaloids as presented in Table 1 and Scheme 1. Among them 2, 4,6 and 13 were found for the first time in Kopsia genus. Three have been proved as new dkaloids: N-carbomethoxy-ll-hydroxy-l2-methoxykopsinaline (lo), N-carbomethoxy-llmethoxy-l2-hydroxykopsinaline (11) and kopsamine N-oxide (12). The other three were not further studied because of insufficient quantities.