Alstonia scholaris R.Br. is grown widely in South-East Asian and South Asian districts. The studies on the constituents have been carried out on the plants originated from Thailand, India, or Pakistan, so far. In order to establish the feature of the component alkaloids in the plant grown in Philippines, the isolation and identification of the alkaloids were attempted on the leaves of A. scholaris in Philippines as well as those from Indonesia, Thailand and Taiwan. 1. Isolation of the new alkaloids. Alschomine and isoalschomine, N_b-C_5 secoalkaloid, were isolated from the leaves from Taiwan and Thailand, along with the known alkaloids, e.g. picrinine, picrarinal and nareline, and the structures were elucidated by X-ray analysis of alschomine. The structures of AsP-5a and 5b, (major alkaloids from the Philippine leaves), were established to be 6,7-seco-alstonamine and N-demethyl-6,7-seco-alstonamine, respectively. AsP-5a seems to be the same compound as 6,7-seco-angustilobine B, recently isolated from A. angustiloba. Along with AsP-5a and 5b, 19-hydroxy-tubotaiwine was isolated from the Philippine leaves. 2. Characteristic feature of the component alkaloids in each district. The picrinine-type alkaloids (Group I) are popular in the leaves from Thailand and Taiwan but not in the leaves from Philippines. The alstonamine-type and seco-alstonamine-type alkaloids are dominant in those from Philippines. From Indonesian leaves, vallesamine and 6,7-seco-alstonamine in Group IV were obtained as major alkaloids, and pseudo-akuammigine, picraline, and N_a-methylburnamine in Group I were isolated instead of picrinine and picralinal in those from Taiwan.