Two homogeneous lines of male and female medicinal yam (Dioscorea floribunda Mart. & Gal.) were grown in experimental plots, to evaluate differences in biomass and yields of tuber and diosgenin. Plants originating vegetatively from female lines had a significantly higher yield of foliage and weight of fresh tuber per plant, yield of dry tuber (60%), and diosgenin per hectare (83%) than from male plants. The highest quality of diosgenin (4.22% of dry weight) in tuber was obtained from the median portion which was 70 and 101% higher than diosgenin in the tip and crown portions, respectively.