This study is to calculate a risk of lung cancer in a cohort of 1411 sarcoidosis cases which were followed for a 3 year period from 1984 to 1987. The physicians were requested to answer the questionnaire about progress of the disease by mail. Excess death was investigated using standardized mortality ratio (SMR). The expected number of deaths was calculated from Japanese sex-age specific mortality rate in 1985, using person-year method. Death from all causes and cancers did not show any excess. SMR being 0.98 and 0.97 respectively. The SMR of lung cancer was 3.26 (male: 5.56, female: 3.03), being statistically significant. The SMR of lung infection was 4.2, with statistical significance. The SMR of other main causes of death in Japan i.e., cerebrovascular accident, ischemic heart diseases and heart failure was less than 0.88. It is probably that sarcoidosis is a risk factor of lung cancer. The SMR of leukemia and uterine cancer was 5.88 and 8.70, respectively, though the observed number of leukemia was too small to conclude how high the cancer risk is among sarcoidosis patients. Gastric cancer, hepatic cancer and colon cancers were not observed.