Study objectives: To determine if interleukin-6 (IL-6), which contributes to the regulation of inflammation is related to oxygen kinetics during maximal CPET and early recovery in patients with sarcoidosis. Participants: Twenty-six patients with sarcoidosis (11 male/15 female, aged 42±11) and 11 healthy volunteers (3 male/8 female, aged 29±5) underwent maximal CPET on a treadmill. Breath by breath analysis was used for measuring oxygen consumption (VO2), anaerobic threshold (AT) and first degree slope at the early phase of recovery. Serum levels of IL-6 were measured before, at peak of exercise, and 15 minutes after exercise with a high sensitivity ELISA method. Results: Patients with sarcoidosis had significantly higher IL-6 serum levels, lower values for VO2 at peak of exercise (VO2 peak % pred 80±17 vs 90±19, p < 0,05), and slower recovery (1±0.289 lt/min/min vs 1.24 ± 0.166, p = 0,003) when compared to healthy subjects. A negative correlation was found between IL-6 serum levels and VO2 peak (lt/min) (r= - 0,483, p = 0,013) and anaerobic threshold (ml/kg/min) (r= -0,507, p= 0,008). There was also found that the mean value of IL-6 serum levels in patients with VO2/t slope < 0.8lt/min/min were significantly higher compared to patients with VO2/t slope ³0.8 lt/min/min (p < 0,05). Conclusion: These data may indicate an important role of the inflammatory process in the pathophysiological mechanisms of exercise limitation in patients with sarcoidosis. Pneumon 2003, 16(2):153-162.