Two bicyclic piperidyl alkaloids (ammodendrine and smipine) and a quinolizidine alkaloid (thermopsine) were identified as major alkaloids of the genus Dichlus. Other piperidyl alkaloids positively identified were bipyridyl, N-methylammodendrineN-acetylhystrine, l-acetyl-l,2,3,4-tetrahydropyridine and piperidinone. The latter two compounds have not been previously reported from the Leguminosae. In the tribe Crotalarieae, the dominance of piperidyl alkaloids appears to be a unique chemotaxonomic character for Dichlus. Our results strongly support the present circumscription and also the isolated position of the genus. An affinity with Melolobium rather than Lebeckia is suggested. © 1988.