The genome of a low equine cell passage equine herpesvirus 2 was partially cloned and physical maps for the restriction endonucleases BamHI, EcoRI, HindIII, and SalI determined. The genome length was estimated to be 192 kilobase pairs (kbp) and no evidence of isomerization was found. Two separate repeat structures were detected: 18 kbp direct terminal repeats; and an unrelated second pair of short internal, indirect repeats at 0.20 and 0.75 map units. Such a genomic structure does not appear to have been reported amongst the herpesviruses--all the genomes that do not isomerize either have repeat structures only at the termini, or if present internally, have only direct repeats.