Epidemiologic studies have been playing frontier roles to explore determinants of sarcoidosis by observing affected persons with the related population. Since 1990, more than 100 epidemiologic papers have been added to the Medline and PubMed databases. Of them, just a few were dated after March 2001. This article is focused on the papers after that time, referring to a number of previous important epidemiologic studies. The review is arranged according to two major epidemiologic categories: (1) host-related findings such as age, sex, race, familial clustering, and lifestyle; and also (2) time- and space-related findings such as exposures, geographical variation, local clustering, climate and seasonal variation, migration, and time-space clustering (transmission).