One hundred and ninety-nine cases of sarcoidosis were diagnosed from July 1970 to December 1976 in a defined geographical area in northern Finland. At the follow-up examination at least 5 years later (range 5-12 years) a chest röntgenogram was obtained from 179 patients (90%) and lung function tests were performed by 169 patients (85%). A normal röntgenogram was achieved by 94 of the 113 patients with stage I sarcoidosis (83%), and by 36 of the 62 patients with stage II (58%). Two patients in the former group (2%) and 14 in the latter (23%) had progressed to the fibrotic stage III, but the fibrosis was usually slight. FEV1 and FVC had increased during the follow-up period, DCO showing the largest number of abnormal results in the final examination. Lung function largely normalized with a normal röntgenogram, whereas the functional outcome was worst where fibrosis had developed. Only two patients had been granted a disability pension because of sarcoidosis. Six patients had died, but none of sarcoidosis. The results show a favourable prognosis for sarcoidosis in this comprehensive series of patients.