BALF ACE levels were assayed in patients with sarcoidosis, and their correlation with lymphocyte percentage and TH/Ts ratio in BALF were analysed. The results showed a positive correlation (r = 0.4453, P < 0.05; r = 0.7085, P < 0.01). BALF ACE level was decreased as patients with active sarcoidosis improved clinically, indicating that BALF ACE level may be a sensitive biological parameter in the diagnosis and disease activity assessment of sarcoidosis.