We report a 68 years old male with a polymyositis associated to HTLV-I. Diagnosis was based on clinical picture, an increased creatin-phosphokinase levels, electromyography and muscle biopsy. The patient had positive HTLV-I antibodies, measured by particle agglutination test, indirect immunofluorescence and polymerase chain reaction in lymphocytes. Skin biopsy showed a mycosis fungoides. Schirmer test and minor salivary gland biopsy showed a dacryosialoadenitis. There was no central nervous system involvement. This patient is the only with positive HTLV-I antibodies, among 18 patients with polymyositis in whom these antibodies were measured.