Preliminary phytochemical investigation of the leaves of Synclisia scabrida indicated the presence of two alkaloids in the water extracts and five alkaloids in the ethanol extracts. The alkaloidal fraction obtained from the cold ethanol extract furnished on column-chromatography, a homogeneous amorphous solid which has been designated as alkaloid C. Alkaloid C showed positive test for alkaloids. The UV and IR spectra and colour reactions of alkaloid C indicated that the compound may be a phenolic bisbenzylisoquinoline alkaloid. All the extracts delayed the onset and shortened the duration of apomorphine-induced stereotyped behaviour in chicks. In addition, 40 mg kg-1 i.p. of the ethanolic extract induced catalepsy in rats. The cold water extract (CWE) synchronized the EEG of the hyperstriatum, optic tectum and the reticular formation while the EMG activity was slightly enhanced. The hot ethanol alkaloidal extract (HEE) inhibited the growth of Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration of HEE on Pseudomonas aeruginosa strains I and II were 5 and 2.5 micrograms/ml while for Staphylococcus aureus strains I and II were 5 and 10 micrograms/ml, respectively. Up to 1 g kg-1 i.p. of the extract failed to induce any lethal effect in chicks and rats. These effects of the leaf extracts of Synclisia scabrida Miers support some of the local uses of the plant by traditional medical practitioners.