A plasmid library of restriction DNA fragments of a Plutella xylostella granulovirus (PxGV) was constructed, which covered all 9 EcoRI and all 19 HindIII fragments, and 18 of 20 PstI fragments. Restriction endonuclease analysis and DNA-DNA hybridization analysis of the cloned viral DNA fragments in the library and the restricted viral DNA fragments were carried out for construction of a physical map of PxGV DNA for ApaI, BamHI, BglII, EcoRI, HindIII, KpnI, PstI, SacII, XbaI and XhoI. The size of PxGV genome was estimated to be 102.2 kb. Location of the left-most DNA fragment on the physical map that contained granulin gene was determined by hybridization using a DNA probe of granulin gene of Trichoplusia ni granulovirus. Four homologous regions interspersed on the genome were also determined by DNA-DNA hybridization analysis.