Three varieties of cotton, LSS, AC.134 and L.11 were studied during developing of cottonseed. Nitrogen, magnesium, chlorophyll, carbohydrates, gossypol and oil were estimated from samples of cottonseed taken at weekly intervals. Carbohydrate reserves depleted with increase in oil, thus indicating a negative correlation while a positive correlation between gossypol and oil was found. Magnesium increased throughout the seed development. Chlorophyll appeared for a short period and then disappeared. Nitrogen reserves though irregular were on the increase throughout the developing period. Maximum oil accumulated in AC. 134 followed by LSS and L.11 varieties.