We detected herpesvirus infection in a male yellow-footed antechinus (Antechinus flavipes) and male agile antechinus (Antechinus agilis) during the period of postmating male antechinus immunosuppression and mortality. Histopathologic examination of tissues revealed lesions consistent with herpesvirus infection in the prostate of both animals. Herpesvirus virions were observed by transmission electron microscopy in the prostate tissue collected from the male yellow-footed antechinus. Herpesvirus DNA was detected in prostate, liver, lung, kidney, spleen, and ocular/nasal tissues using a pan-herpesvirus PCR targeting the viral DNA polymerase. Nucleotide sequencing identified a novel herpesvirus from the Gammaherpesvirinae subfamily that we have tentatively designated dasyurid herpesvirus 1 (DaHV-1).