The pharmacological effects of an aqueous extract of Sphenostylis stenocarpa seed were investigated in albino mice. Acute toxicity testing indicated the LD50 to be 570 mg/kg, i.p. The extract significantly potentiated pentobarbitone-induced sleeping time. Increasing the dose of the extract correspondingly increased the sleeping time up to a dose of 60 mg/kg i.p. The extract did not protect mice from convulsions and death resulting from the administration of strychnine (2 mg/kg, i.p.) or leptazol (100 mg/kg, s.c.).