Erythema multiforme was reported in a Welsh Pony. The pony suddenly displayed pruritic, more or less bilateral symmetrical, alopecic and erosive skin lesions over the entire body. There was edema of the ventral abdomen and preputium. Histopathological findings included hydropic degeneration and apoptotic keratinocytes at all levels of the epidermis. Possible initiating causes are discussed. The pony was treated with penicillin and prednisolone and full hair regrowth was seen within three months.