A 5 ? 5 diallel cross experiment was conducted involving the verities i.e. AC-134, MS-39, 124-F, CIM-473, and LA-85-52-2 to evaluate the type of gene action involved in the inheritance of various morphological and yield contributing traits in upland cotton. The analysis of variance revealed that differences between genotypes for all the traits were highly significant. The results of joint regression analysis revealed that the data for all the traits were fit for simpole additive dominance model.The genotype AC-134 carried maximum dominant genes for plant height, number of sympodial branches and ginning out turn. The genotype 124-F possessed maximum number of dominant genes for number of monopodial branches.The genotype CIM- 473 was found to be the best general combiner for number of bolls per plant, boll weight while the genotype MS-39 seemed to be the best general combiner for plant height. From the above results it was suggested that the plant traits could be improved by simple selection procedure because they are controlled by additive type of gene action as far their phenotypic expression is concerned.