Silk seed is the basic requirement for silk production. This article describes the work of silkworm breeding in Pakistan. Four new silkworm varieties were developed from imported F1 hybrid silk seed by inbreeding and selection to produce a F1 hybrid for commercial fearing in Pakistan. 1,500 boxes of F1 hybrid disease free silkworm seed was produced in 1988 and 2,100 boxes in 1989, for the first time in the country for distribution amongst the farmer for rearing. During breeding and selection of the bi-voltine races sex limited mutants were also selected for further research.