Based on previous rat feeding experiments it was concluded that the saga bean contains a toxic principle in the oil fraction which cannot be destroyed by the simple process of household boiling in water. Three kinds of heat treatments with temperatures higher than that of boiling water, were applied to the sagabeans, viz. roasting, deep frying and pressure-cooking. The so-treated sagabeans were incorporated into experimental rat diets for a Protein Efficiency Ratio study, with and without supplementation with methionine and threonine. Comparing the results obtained with boiled, completaly defatted sagabeans, the present experiments by heat treatments reduce or very probably eliminate the toxic principle.