Cassia occidentalis is an annual shrub found in many countries including India. Although bovines and ovines do not eat it, parts of the plant are used in some traditional herbal medicines. Several animal studies have documented that fresh or dried beans are toxic. Ingestion of large amounts by grazing animals has caused serious illness and death. The toxic effects in large animals, rodents and chicken are on skeletal muscles, liver, kidney and heart. The predominant systems involved depend upon the animal species and the dose of the beans consumed. Brain functions are often affected. Gross lesions at necropsy consist of necrosis of skeletal muscle fibres and hepatic centrilobular necrosis; renal tubular necrosis is less frequent. Muscle and liver cell necrosis is reflected in biochemical abnormalities. The median lethal dose (LD(50)) is 1 g/kg for mice and rats. Toxicity is attributed to various anthraquinones and their derivatives and alkaloids, but the specific toxins have not been identified. Data on human toxicity are extremely scarce. This review summarizes information available on Cassia toxicity in animals and compares it with toxic features reported in children. The clinical spectrum and histopathology of C. occidentalis poisoning in children resemble those of animal toxicity, affecting mainly hepatic, skeletal muscle and brain tissues. The case-fatality rate in acute severe poisoning is 75-80 per cent in children.