Heterosis and genetic architecture of oil content in mustard (Brassica juncea Coss) was studied in a complete diallel set of eight parents including reciprocals. Combining ability analysis indicated significance of GCA, SCA and RCE variances. Equal magnitude of GCA and SCA indicated the role of both additive and non-additive type of gene action. Contribution of RCE to the total variances was also appreciable. Highest mean value, highest heterosis over the better parent and high SCA effects were observed in cross combination of RC-5 × T-16. T-16 was found to be the best general combiner followed by F-58.
