To determine whether HTLV-I infection is associated with uveitis, we investigated the bronchoalveolar lavage fluid (BALF) cells in 23 patients with uveitis. Of these, sarcoidosis was diagnosed in 13 patients, but could not be confirmed in the remaining 10 patients (non-sarcoidosis). Three of 13 patients (23.1%) with sarcoidosis and 7 of 10 non-sarcoidosis patients (70.0%) were HTLV-I seropositive. In BALF, no significant differences were observed between the HTLV-I seropositive and seronegative patients. However, in non-sarcoidosis patients, total cell counts, CD3+ and CD+ HLA-DR+ cells in BALF were significantly higher in seropositive patients than in seronegative patients. CD3+ CD25+ cells in BALF were markedly increased in 3 of 7 non-sarcoidosis seronegative patients. These findings indicated that BALF lymphocytes in HTLV-I seropositive non-sarcoidosis patients were more activated than those in seronegative non-sarcoidosis patients, supporting the hypothesis that HTLV-I infection may be associated with uveitis.