SUMMARYThe genome of an Australian isolate of equine herpesvirus type 1 (equine abortion virus) has been analysed using the restriction endonucleases EcoRI, BglII and BamHI, and a physical map constructed. Terminal fragments were identified by exonuclease treatments, and linkage of fragments was deduced by a combination of single-and double-digest experiments and cross-blot hybridizations. The genome has a mol. wt. of 100 x 10 6 and is comprised of a short unique region bounded by repetitive sequences, which is present in both orientations in approximately equal amounts in the DNA population, and a long unique region existing in only one orientation.