Six generations (P$_1$, P$_2$, F$_1$, BC$_1$, BC$_2$ and F$_2$) of four bivoltine silkworm crosses (SKAU-R-1 ${ imes}$ Yakwei, SKAU-R-6 ${ imes}$ Yakwei, CSR$_2$ ${ imes}$ CSR$_4$ and SH$_{6}$${ imes}$ NB$_4$D$_2$) were evaluated in a completely randomized block design with 5 replications for each treatment. The generation mean 2 in respect of 3 metric traits (single cocoon weight, single shell weight, and shell ratio ％), were subjected to Cavallis joint scaling test. Additive dominance model was found to be adequate in CSR$_2$${ imes}$CSR$_4$ and SH$_{6}$${ imes}$ NB$_4$D$_2$ for single cocoon weight and shell weight and SKAU-R-6 ${ imes}$ Yakwei for shell ratio(％). Whereas, in rest of the crosses epistasis was evident in the traits under investigation. Magnitude of additive gene effect (d) was greater than dominance(h) in SH$_{6}$${ imes}$NB$_4$D$_2$ and SKUA-R-6${ imes}$Yakwei for shell ratio (％) and in CSR$_2$${ imes}$ CSR$_4$ for shell weight. Thus selection for these traits in early segregating generations of these crosses would be effective for obtaining considerable genetic gain. gain.