The chemical composition of dry seeds of four varieties, pods, stalks and leaves of winged beans (Psophocarpus tetragonolobus) was determined. The seeds had a high range of protein (27.8-36.6%) and fat (14.8-17.9%), which were similar to soybeans. the seeds contained high phosphorus, calcium and magnesium. The leaf was highest in protein content (33.7%) of all the parts studied except for the seeds. The protein and fat content of pods decreased as pods ripened. the calcium content in the leaf was much higher than in the other parts. Protein was extracted sequentially with 2% NaCl, 30% isopropyl alcohol, 4% lactic acid and 0.5% KOH from dry seeds of four varieties of winged beans. The NaCl extract showed the highest range of protein concentration (60.2-77.6%). The NaCl extract was separated into two fractions based on solubility in water. the amino acid composition of the flour from the seeds and of the two fractions from the NaCl extract were determined. Contents of lysine, aspartic acid, glutamic acid and leucine were large, while the sulfur-amino acid content was small. Trypsin and chymotrypsin inhibitory activities of 2% NaCl extract from the seeds were determined, and chymotrypsin inhibitory activity was higher than the trypsin.