PYRROLIZIDINE alkaloids are produced by a number of common plants including Senecio and Heliotropium species. They have been implicated in cases of bread poisoning in man in South Africa1, and the infusion of certain of these plants to make bush teas is believed to cause veno-occlusive disease in children in the West Indies2. Grazing animals are frequently affected by these hepatotoxins, and the disease has therefore been closely studied during experiments on domestic and laboratory animals, especially rats; but relatively little is known of the effects on man. The toxic effects of heliotrine and the resulting depression of RNA, DNA and protein synthesis in human liver cells in culture have been studied recently3.