A case of conjunctival lymphoma in a 4-year-old Siberian husky is reported. A large red mass protruding from the conjunctiva of the upper eyelid of the right eye was present. Irritation, blepharospasm and epiphora were revealed on initial ophthalmic examination. After anti-inflammatory treatment, surgery was performed. Histologically, the mass consisted of large polygonal cells with a high nucleus to cytoplasm ratio, moderate amounts of slightly eosinophilic cytoplasm, pleomorphic nuclei with vesicular chromatin and prominent multiple nucleoli. Mitotic figures were frequent. Approximately 70% of the neoplastic cells were CD3 positive and CD79alpha negative. On the basis of histologic and immunohistochemical findings, a diagnosis of intermediate-grade, diffuse large-cell lymphoma with T-cell immunophenotype was made. The surgical area healed uneventfully and, although chemotherapy was not received, after 12 months the dog exhibited no recurrence. To the authors' knowledge, this is the first report of unicentric extranodal conjunctival lymphoma in a dog.