The diallel analysis technique allows the breeder to estimate the rela-tive importance of general and specific combining ability for important traits in terms of the nature of gene action. Information on these systems is of value in the development of soybean hybrids as well as in the development of pure-line varieties. In this study, a primary objective was to determine the relative magnitudes of general and specific combining ability estimates for protein and oil content in four soybean cultivars grown in Oklahoma.