Textbooks of clinical medicine often begin with "epidemiology" of the disease by describing the distribution of patients' characteristics in terms of age, gender, race, and so on. As a result, many clinicians erroneously think the description of such distribution is a role only for epidemiology. The real role of epidemiology, however, is to search for the determinants of and ways to prevent the disease. In this article, the recent informative papers on the epidemiology of sarcoidosis are reviewed in the light of modern sarcoidology.