Studies on 216 cultivars of Dioscorea alata L. over a three-year period provided an understanding of the flowering deficiencies and fertility status of this dioecious species. The majority of the cultivars did not flower. Female flowering was erratic and significantly less than male flowering due to their scanty occurrence among cultivars. The flowering periods of the two sexes were distinctly different, resulting in non-synchrony of the male and female phases. Flower production of the sexes showed a great numerical disparity, the females producing much fewer flowers. Withering of inflorescences, non-maturing of buds, and non-opening of mature buds were widespread among females whereas among males they were less common. While most of the female cultivars were sexually sterile, the males were largely fertile. Thus, the factors affecting sexual reproduction and seed set in D. alata were primarily the flowering deficiencies of the species and the critical factor was the sexual sterility of the female cultivars.