In a group of 105 patients suffering from various pulmonary diseases we have previously observed quantitative and qualitative differences between alveolar macrophages from smokers and non-smokers. In this study, we compared the cell population of bronchoalveolar lavage (BAL) fluids in non-smoking, and smoking patients suffering from pulmonary sarcoidosis. Cell yield was significantly higher in smokers than in non-smokers: (P less than 0.02), lavage fluids of smokers contained 83% of macrophages and 14% of lymphocytes, as compared with 60% and 34% respectively in non-smokers (P less than 0.002). However, the total number of lymphocytes was not significantly different between the two groups. Alveolar macrophages from smokers were bigger and contained large pigmented lipoproteinic inclusions. Complementary cytochemical studies showed that lipofuscins were the principal constituent of these intracytoplasmic inclusions. In conclusion, cigarette smoke increases the number and alters the structure of the alveolar macrophages of patients with sarcoidosis, as well as in other chronic respiratory disease as previously shown. The mechanism responsible for the increased lipofuscins concentration in the alveolar macrophages of smokers remains to be determined.