Among 50,784 new immigrants entering Vaud Country, Switzerland, between 1988 and 1990, 674 abnormalities were discovered by mass miniature X-ray screening on arrival (424/43,803 foreign workers, 238/4512 refugees and 12/2469 foreign students). 2043 refugees had no radiological examination. After clinical examination, tuberculosis (TB) was considered the likely diagnosis in 256 cases, of which 132 were offered an antituberculous treatment according to the current recommendations of the Swiss Association against TB. 34 of the subjects were smear- or culture-positive (5% of all radiological abnormalities, 0.08% of all immigrants). Only 46 subjects had any clinical complaint. Among foreign workers, 0.18% were carriers of tuberculous lesions needing a treatment; the proportion was 1.22% among refugees. By ethnic origin, the proportion is highest among Africans (1.43%), followed by Turks (1.04%), subjects from the Middle East (0.62%), Yugoslavia (0.55%), Portugal and Spain (0.14%). Mass miniature X-ray screening for TB in immigrants from high prevalence countries entering Switzerland still detects a majority of asymptomatic cases and seems an easy means of preventing the transmission of TB to members of the same community.