Two supposedly Strychnos-based Semai Senoi dart poisons from Western Malaysia, ipoh akar and lampong, and their accompanying plant materials have been re-investigated botanically, chemically, and pharmacologically. The two poisons contained tertiary and quaternary alkaloids, including strychnine and bis-quaternary dimeric bases, and also cardiotonic glycosides. The dominant pharmacological activity of the highly toxic ipoh akar poison was convulsant. The weaker lampong poison had muscle-relaxant activity of the curarizing type. The alkaloids of the two poisons were almost certainly derived from Strychnosignatii Berg. (S. ovalifolia Wall. ex G. Don) and not from S. vanprukii Craib to which the accompanying plant materials probably belong, while the cardiotonic glycosides of the two poisons came from Antiaris toxicaria Lesch. The quaternary alkaloids of both S. ignatii and S. vanprukii have muscle relaxant activity.