Abstract: The newly established ovarian cell line of Bombyx mori, DZNU-Bm-12 was tested for its susceptibility to homologous nucleopolyhedrovirus, BmNPV. The BmNPV was serially passaged in the cell line for five times along with the other four cell lines Bm-1, Bm-16 and Bm-17 which is established in our laboratory and Bm-5 is a widely used cell line. All the cell lines are susceptible to BmNPV. The overall range of BmNPV infection during serial passaging was more than 90% was observed in Bm-1, Bm-5 and Bm-16, whereas in Bm-12 and Bm-17 it was between 77 and 89%. The average number of OBs/infected cell was 16-19 in Bm-1, Bm-5 and Bm-16 but in Bm-12 it was 9-13 and only 7-8 in Bm-17.