The incidence of tuberculosis (TB) presenting to the University Hospital, Geneva, Switzerland, was studied over 2 years. Clinical data on all children receiving antituberculous drug therapy was collected. Of the 43 identified cases, 42% had active disease (i.e. clinical evidence of organ involvement), the remaining 58% being asymptomatic. All 43 children originated from countries other than Switzerland. Symptomatic, drug induced hepatitis necessitated temporary interruption of therapy in 2 children (5%). Contact screening yielded three new cases of pulmonary TB, three previously diagnosed cases and seven instances of a positive medical history in relatives living in other countries. Of the 34 families in this study, contact screening could not be completed in 8. The results of this study indicate that children with TB are primarily associated with families originating from countries other than Switzerland, particularly those in which TB remains endemic. Tuberculin skin testing should therefore be targeted at this group. Contact tracing has also been shown to be beneficial.