Eight bivoltine inbred lines of silkworm Bombyx mori L. viz., AP8, AP10, AP17 and AP18 with marked female and plain male larvae and AP1, AP54, AP71 and AP72 with all plain larvae synthesized from Chinese commercial hybrids were evaluated for their general combining ability (gca), specific combining ability (sca) and reciprocal effects for eight quantitative traits. The line AP18 was found to be best general combiner by virtue of significant positive and positive gca effects for seven out of eight traits studied followed by the lines AP10, AP8 and AP17. Seven hybrids recorded significant positive and positive sca effects for all the traits under study reflecting the interaction of alleles, additive and non additive gene action and dominant effects expressed by genes. Among the 28 reciprocal hybrids, AP54$ imes$AP18 and AP1$ imes$AP17 revealed significant reciprocal effects for the six traits followed by AP54$ imes$AP8 for five and AP10$ imes$AP71 for four traits.