The results of examination of 757 contacts of 186 tuberculosis index cases seen at Ealing Chest Clinic over a period of 7 years (1968--1974 inclusive) are reviewed. The incidence of disease in non-close contacts was low and further analysis was restricted to 574 close contacts. The morbidity in this group was 9%. Asian contacts and contacts aged 15--30 years were at the greatest risk. Fourteen per cent of 151 contacts of respiratory cases positive on direct smear developed disease. The same group had the highest incidence of 'positive' tuberculin skin tests (Heaf grades 2--4). Five per cent of non-Asian contacts and 1% of Asian contacts had disease at initial examination, the excess morbidity in Asian contacts being due to disease diagnosed during follow-up.