Pharmacodynamic effects of ethyl 7-chloro-2,3-dihydro-5-(2-fluorophenyl)-2-oxo-1H-1,4- benzodiazepine-3-carboxylate (CM6912), a new benzodiazepine derivative, and its main metabolites (CM6913 = M1, CM7116 = M2) on the peripheral systems were investigated in several species of animals. In pentobarbital-anesthetized rabbits, CM6912 and M2 (1 or 5 mg/kg, i.v.) had little effect on blood pressure, heart rate and ECG, but it slightly reduced the respiration rate. M1 decreased the heart rate without affecting respiration, blood pressure and ECG. In conscious rabbits, CM6912 and M2 (1 mg/kg, i.v.) did not affect respiration, blood pressure, heart rate and ECG, but M1 (1 mg/kg, i.v.) increased the heart rate. CM6912 (5 or 30 mg/kg), when administered orally, also increased heart rate. In pentobarbital-anesthetized dogs, CM6912 and its metabolites (5 mg/kg, i.v.) decreased respiration and heart rate without affecting blood pressure and ECG. CM 6912 (5 mg/kg, i.v.) did not affect cardiovascular responses to the carotid occlusion, vagus stimulation, and pre- and post-ganglionic stimulation of cardiac ganglion in anesthetized dogs. CM6912 and its metabolites affected neither the spontaneous contraction nor the heart rate of isolated rabbit atria. These compounds also had no action on isolated aortic strips from rabbits. CM6912 and its metabolites did not affect the muscle tone of isolated guinea pig intestine, and it had no effects on the contractile responses to acetylcholine, histamine, serotonin and barium chloride. In isolated rabbit intestine, CM6912 and M2 slightly reduced the amplitude of contraction, while M1 had no effect. CM6912 and its metabolites did not affect the spontaneous motility of isolated non-pregnant and pregnant rat uteri as well as in situ non-pregnant rat uterus and isolated guinea pig vas deferens, including the contractile response to adrenaline. CM6912 and M2 relaxed isolated guinea pig trachea strips only at high concentrations. CM6912 and its metabolites did not affect the contractile responses of isolated rat diaphragm to electrical stimulation of the phrenic nerve. CM6912 (2 or 10 mg/kg, p.o.) did not affect the rat renal and hepatic functions. CM6912 influenced neither blood coagulation in rabbits nor blood hemolysis in rats. CM6912 and its metabolites did not affect the pupil size and its light reflex, and they did not produce a local anesthesia and edema. The present results suggest that CM6912 and its main metabolites exert only slight effects on the peripheral systems in animals.