A BSTRA CTThe effects of heat treatments, namely microwave, infrared, hot air oven, autoclaving and cooking in boiling water, on trypsin inhibitor and haemagglutinating activities, tannin and phytate contents, essential amino acid composition and quality of proteins in winged bean, were investigated. The infrared, autoclaving and boiling-water treatments destroyed most of the trypsin inhibitor and haemagglutinating activities, and reduced the level of tannins. However, the microwave and oven heat treatments had no effect on these constituents of winged bean meal. Lysine and valine contents in the meals from infrared, autoclaving and cooking in boiling water treatments were lower than in untreated meal. There was a significant loss of threonine and arginine due to cooking of beans in boiling water. None of the treatments had any effect on phytate content.Rats fed on untreated, microwave-treated and oven-heated meal diets had low dry-matter intakes and lost weight significantly. However, remarkable improvements in dry-matter intake and weight gain were recorded for the diets containing meal from infrared, autoclaving and boiling-water treatments. The digestibility of proteins in the meal improved from 50 to 84% as a result of infrared and boiling-water treatments, whereas a noticeable decrease in protein digestibility was observed in ovenheated meals. There was a significant improvement in biological values and net protein utilisation values for the diets containing meals from infrared, autoclaving and boiling-water treatments over those of a diet having untreated meal.