Fermented leaves of Cassia obtusifolia 'Kawal' were mixed in the food of broiler chicks at concentrations of 25, 50 and 100 g/Kg and then fed to chicks from 1 day to 8 weeks of age. Growth rate was depressed in relation to the concentration of Kawal. Lesions of an inflammatory-degenerative type were seen in the proventriculus, intestine, liver, heart, lungs and kidneys, their severity increasing with the amount of Kawal eaten. These were accompanied by similar increases in the activities of lactate dehydrogenase, alkaline phosphatase, glutamate oxaloacetate and glutamate pyruvate transaminases and in the concentrations of bilirubin, potassium, phosphorus, total lipids and carotenes in the blood and dose-related decreases in total protein, albumin, cholesterol, globulin, sodium, calcium and alkaline phosphatase in the blood. Birds fed on Kawal tended to become anaemic but white blood cell counts increased. It is concluded that Kawal even at an inclusion rate of 25 g/Kg is unacceptable as a protein supplement.