gp64 glycoprotein, an abundant and the only membrane glycoprotein encoded by the baculovirus genome, contains a signal peptide sequence at N-terminus, a transmembrane anchor at c-terminus and a ectodomain between them. The efficient signal sequences and the transmembrane anchor sequences of AcMNPV gp64 gene have been exploited in baculovirus expression system. Using 1.3 kb AcMNPV gp64 gene coding sequence as the probe, the nucleotide sequence of BmNPV gp64 gene was determined, and a 1530 nucleotide open reading frame flanked by an AT-rich sequence was identified that could encode a polypeptide with 509 amino acid residues. Computer analysis indicated BmNPV gp64 gene is 84.3% identical to AcMNPV at the level of nucleotide sequence and 94.7% identical at the level of predicted amino acid sequence.