Abstract: The value of cottonseed is determined largely by oil and protein content. Determining the inheritance of these traits and studying their influence on lint yield and fiber properties might improve breeding program efficiency. The main objective of this study was to determine the inheritance of oil and protein content and the influence of environment on oil and protein content in cotton (Gossypium hirsutum L.). For this investigation, Sure Grow 125 (P1), PAUM 401 (P2), F1, F2 and backcross generations were planted in a randomized complete block design at two locations in Turkey. Environment influenced the level of oil and protein content far more than did the genotypes. Generation mean analysis indicated that dominance (h), additive x additive (i) and dominance x dominance (l) effects were the main source of genetic variations for the oil and protein content. Since nonadditive effects were predominant, selection for these traits could be made in advanced generation.