Two members of mouse heat shock protein 70 family (M.W. 70 kDa) were investigated for the possible induction by bovine papillomavirus DNA transfection. One gene is expressed in male germ line as developmental stage specific manner (hsc 70), and the other is a heat-inducible hsp 70 gene, expressed in nearly all cell types. The promoter regions of these genes were isolated and linked to promoter-less CAT gene. CAT-recombinant DNAs were transfected to mouse fibroblast cells, and the CAT activities were analyzed. By the heat shock, hsc 70 promoter showed two fold increased CAT activity as compared to normal condition. When BPV DNAs were cotransfected, CAT activity was also increased by two fold after 24 hrs. This increased CAT activity was also shown when E2 trans-activator gene of BPV was cotransfected. Heat-inducible hsp 70 promoter showed higher CAT activity than hsc 70 promoter in normal condition, however, transcriptional activity of hsp 70 promoter was not affected by heat shock or BPV DNA transfection.