In 32 patients 8 years after recovery from unilateral empyema treated by chest tube drainage the pulmonary function was studied. The most frequently occurring abnormalities were diminished dynamic lung compliance, diffusion capacity and perfusion evaluated by scintigraphy. Restrictive patterns were observed only in 2 patients. The greatest abnormalities were observed in patients with extensive empyema, in patients with delay in drainage and with residual radiological changes after recovery.