Violacein was isolated from Chromobacterium violaceum, a soil Gram-negative bacterium collected from the forest water body soil sample from Kolli Hills of Tamil Nadu, India. In the present study the anti-diarrhoeal and ulcer-protective properties of violacein were investigated in Wistar rats using castor oil, magnesium sulphate and ethanol. The intestinal transit in rats was significantly (P < 0.001) reduced and gastric emptying was delayed; 40 mg/kg of violacein elicited a greater anti-motility activity than 0.1 mg/kg of atropine. Violacein exhibited ulcer-protective properties against ethanol-induced ulceration in rats with maximal anti-ulcer activity at 40 mg/kg. Violacein also exerted significant anti-enteropooling effects, causing a dose-related inhibitory effect on castor oil-induced enteropooling in rats. A profound anti-diarrhoeal activity was observed when violacein was tested in diarrhoeic rats. The frequencies of defaecation as well as the wetness of the faecal droppings were significantly reduced. Furthermore, violacein (40 mg/kg) produced 87.84% inhibition of castor oil-induced diarrhoea in rats. The results suggested that violacein can be used for the treatment of diarrhoeal and ulcer-related diseases.