The general pharmacological properties of YJA20379-1 2-dimethylamino-4,5-dihydrothiazolo[4,5:3,4]pyridol[1,2-a]benzoimidazole, a novel proton pump inhibitor with antiulcer activities were investigated in mice, rats, guinea pigs and rabbits. YJA20379-2 at oral doses of 50, 100 and 200 mg/kg did not affect the general behaviour, hexobarbital hypnosis and motor coordination in mice. The drug did not have analgesic or anticonvulsant action at 200 mg/kg. Locomotor activity and body temperature were not influenced at 100 mg/kg. At a concentration up to 2{ imes}10^{-4} g/ml$, YJA20379-2 did not produce any contraction or relaxation of isolated preparations, such as the rat fundus, the guinea pig ileum and the rat uterus, and did not antagonize the contractile response to several spasmogens, such as histamine, acetylcholine, serotonin and oxytocin. At dosages up to 200 mg/kg p.o. YJA20379-2 did not affect the pupil size of mice. Intestinal propulsion of mice was not affected up to 200 mg/kg p.o. and the drug did not affect urinary excretion at 100 mg/kg p.o. These results indicate that at dosages up to 100 gm/kg p.o. YJA20379-2 was found not to affect this pharmacological profile. However, at 200 mg/kg the drug lowered body temperature and showed decreased in locomotor activity and urine volume.