Manifestation of heterosis in interbreed crosses of high, medium, low, and control lines selected for pupal wt. in silkworm is reported. Significant pos. heterosis over better parent in the selected and correlated traits was obtained due to the wider genetic distance noticed in Pure Mysore (multivoltine) and NB18 (Bivoltine). Whereas, the magnitude of heterosis varied among interbreed crosses which involved all 3 types of gene effects (additive, dominance, and epistatic interactions). The present study indicated that heterosis was more pronounced in the crosses involving bivoltine which happen to be either low male or female component and is clearly demonstrated in the heterosis averaged over male and female parents. Higher pupal wt. does not necessarily result in higher heterotic values so, while selecting the parents for com. exploitation differential pupal wt. should also need to be considered
