The objective of this study was to determine the prevalence of tuberculous infection and the incidence of active tuberculosis in homeless men attending a shelter-based clinic and to examine risk factors for acquisition of infection and development of active disease. The design was a prospective cross-sectional survey. Men were evaluated by standardized interviews using a questionnaire. Where indicated, skin testing with PPD, collection of sputum for smear and culture for acid-fast bacilli, and chest x-ray films were performed. The setting was an on-site clinic at a men's shelter in New York City. The patients were men attending the clinic for physical examinations for the work program or requesting evaluation of various medical problems. A total of 1,853 men were evaluated over a 73-month period. The overall rate of infection was 42.8 percent, including 27.0 percent with a positive PPD test, 9.8 percent with a history of a positive PPD test, and 6.0 percent with active tuberculosis. Increasing age, length of stay in the shelter system, black race, and intravenous drug use were found to be independently associated with tuberculous infection. Age, length of stay in the shelter system, and intravenous drug use were independently associated with active tuberculosis. We achieved a compliance rate of 36 percent completing treatment and 13 percent receiving treatment at the conclusion of the study.