Edinburgh hostel dwellers have been regularly screened for pulmonary tuberculosis since 1957. Sixty-eight cases were notified during the 7 years 1976-1982: 42 (65%) were detected by 4687 hostel survey X-rays, and a further 26 presented with symptoms. Disease was more advanced in the symptomatic hostellers both by radiological and bacteriological criteria with twice as many being sputum smear positive (58% vs. 26%). Full clinical details were available for 65 of the 68. Four were diagnosed at post mortem examination and two had chemotherapy stopped because the disease was considered inactive. Of the remaining 59 eligible for treatment, 47 (80%) received a complete course of adequate chemotherapy; 16 as hospital in-patients, 26 first in hospital and then under out-patient supervision and five simply as supervised out-patients; none relapsed. Twelve (20%) of the 59 defaulted from supervision after a mean follow-up period of 2.4 months.