Cutaneous epitheliotropic T-cell lymphoma in the dog is a rare neoplastic condition with unknown aetiology. The dermatitis is characterized by infiltration of neoplastic T lymphocytes with a specific tropism for the epidermis and the adnexal structures. The different clinical and histological forms (mycosis fungoides, pagetoid reticulosis and Sézary syndrome) are reviewed. The disease in the dog resembles the human syndrome, but in 80% of the canine cases, neoplastic cells are CD4(-)/CD8(+) versus CD4(+)/CD8(-) in 90% of the human patients. Prognosis is poor with a survival time from few months to 2 years. Treatments frequently have a low efficacy. New protocols using lomustine may improve the poor prognosis of the disease.