General and specific combining ability effects of six bivoltine breeds of silkworm (Bombyx mori L.) were evaluated for six quantitative characters through diallel method wherein parents, $F_{1}s$ and reciprocals are involved. The breeds $APS_{11};and;APS_{2}$ were found to be the best general combiners for most of the traits studied. The high estimates of specific combining ability (sca) variance (${sigma}^{2}s$) compared to general combining ability (gca) variance (${sigma}^{2}g$) indicated the predominant role of non-additive gene action in the control of all the characters. Positive sca effects for majority of the traits were expressed by the combinations $APS_{13}{ imes}APS_6,;APS_{13}{ imes}APS_2,;APS_{11}{ imes}APS_6;and;APS_5{ imes}APS_2$ out of 15 crosses. Among the 15 reciprocal crosses studied, the combination $APS_8{ imes}APS_{13}$ showed positive reciprocal effects for all the six traits. With both the parents $APS_5;and;APS_2$ being good general combiners the hybrid $APS_5{ imes}APS_2$ showing high sca effects is recommended for commercial use.