Neoplastic adnexal disease represents one of the most frequently encountered and therapeutically challenging ophthalmic problems of horses. This paper reviews current concepts in equine periocular neoplasia. Specifically, a literature-based review of the aetiopathogenesis of the most common tumours to affect the equine eyelid (squamous cell carcinoma, sarcoid, melanoma and lymphosarcoma) is provided. Current and emerging treatment modalities, including photodynamic therapy, are reviewed.