Aqueous and organic extractions of ground seeds of Cassia occidentalis were obtained. Chickens were dosed with extracted material to assess the toxicity of the extracts. Organic extracts with methanol, ethanol, chloroform, ethyl acetate, and benzene were ineffective in removing the toxin from the seeds. Aqueous extractions, using 25 mM sodium bicarbonate or 250 mM sodium citrate, removed the toxin from the seeds, but left the toxin bound to particulate matter in the extract. Addition of Triton X-100 to the aqueous buffers effectively solubilized the toxin from the particulate matter. Signs of intoxication in the chickens were loss of weight, weakness, diarrhea, hypothermia, occasionally ataxia, and recumbency; then death. Gross lesions included paleness of skeletal and cardiac muscles and congestion of the liver. Microscopic lesions in muscle tissue were vacuolation, proliferation of sarcolemmal nuclei, and separation of myofibrils. Electron microscopic examination revealed disruption of mitochondrial cristae and swelling and rupture of mitochondria.