The general pharmacological studies on cefmenoxime (CMX, SCE-1365) produced the following results.<BR>The agent had no muscle-relaxant, anticonvulsive, hypnosis-potentiating, analgesic, hypothermic, antipyretic, diuretic or antidiuretic, intestinal motility- or gastric secretion-disturbing or anti-inflammatory activity in mice or rats at a subcutaneous dose of 250 mg/kg. Nor was there any effects on the spinal reflex or neuromuscular transmission in anesthetized cats at an intravenous dose of 250 mg/kg, on the electroencephalogram in unanesthetized, paralyzed cats at an intravenous dose of 250 or 500 mg/kg, or on the electroencephalogram or behavior in conscious, unrestrained cats at a subcutaneous dose of 250 mg/kg. Cefmenoxime at a subcutaneous dose of 1, 000 mg/kg but not 500 mg/kg significantly increased urinary sodium excretion with a tendency of increasing urine volume in rats, probably because of its sodium salt. The blood pressure of anesthetized cats was transiently decreased by rapid intravenous injections of 50 mg/kg or higher. with a slight increase in the heart rate and amplitude of respiratory movements. The blood flow of the vertebral and femoral arteries in anesthetized dogs was transiently increased by a rapid intravenous injection of 250 mg/kg, with a slight and transient fall in blood pressure. Blood pressure response to norepinephrine, isoproterenol, acetylcholine, histamine or carotid artery occlusion, or nictitating membrane contraction evoked by electrical stimulation of the preganglionic fibers of the cervical sympathetic nerve in anesthetized cats was not affected by cefmenoxime in an intravenous dose of 200 mg/kg. In in vitro experiments, no effect on guinea-pig atria or various smooth muscle preparations, except rat uterine preparations, was found even in a high concentration of 10^-3 g/ml; in both virgin and pregnant rat uterine preparations, the height and frequency of spontaneous contractions were slightly inhibited by cefmenoxime in concentrations of 5 × 10^-4g/ml and higher. No spasmolytic activity against acetylcholine-, histamine-or BaCl2-induced spasm was found at a concentration of 10^-3 g/ml of cefmenoxime.<BR>In conclusion, these results suggest that cefmenoxime does not cause any untoward effects on the central nervous, autonomic nervous, cardiovascular, gastrointestinal, analgesic-antiphlogistic or diuretic mechanism at its estimated clinical dose (1, 000 mg/man per day).