A phytochemical investigation of the chloroform extract of the stem bark of Strychnos soubrensis Hutch. et Dalz. (Loganiaceae) resulted in the isolation of four alkaloids. Three of them were identified as strychnobrasiline, strychnofendlerine, and isosplendine. The fourth one is a new alkaloid for which we propose the structure 14-β-hydroxy-strychnobrasiline. The African species of Strychnos has been the object of systematic research in recent years. However, whereas some species have been extensively investigated, others have received little or no attention. Therefore, so far, the knowledge of the African Strychnos species is not complete. In an effort to supply some of the missing information, we investigated the alkaloids of the stem bark of Strychnos soubrensis Hutch. et Dalz. Strychnos soubrensis (1) (section Lanigerae) is a liana or scandent shrub, 10-50 m long, up to 40 m high, climbing in trees. It is widely distributed in the West African rain or secondary forests, often on river banks, at altitudes of 0-1000 m. The bark is pale grey to dark brown with large lenticels. Preliminary phytochemical (2) and pharmacological (3,4) studies revealed that the small amount of alkaloids present (<0.1%) combined a weak strychnine-like (convulsant) activity with a much stronger muscle-relaxant effect.