SETTING: The largest cities in Benin, Burkina Faso, Cameroon and Central African Republic.OBJECTIVE: To demonstrate the feasibility and document the effectiveness of household contact investigation and preventive therapy in resource-limited settings.DESIGN: Children under 5 years living at home with adults with bacteriologically confirmed pulmonary tuberculosis (TB) were screened using questionnaire, clinical examination, tuberculin skin test and chest X-ray. Children free of active TB were offered preventive treatment with a 3-month rifampicin-isoniazid (3RH) or 6-month isoniazid (6H) regimen in Benin. Children were followed-up monthly during treatment, then quarterly over 1 year. Costs of transportation, phone contacts and chest X-rays were covered.RESULTS: A total of 1965 children were enrolled, of whom 56 (2.8%) had prevalent TB at inclusion. Among the 1909 children free of TB, 1745 (91%) started preventive therapy, 1642 (94%) of whom completed treatment. Mild adverse reactions, mostly gastrointestinal, were reported in 2% of children. One case of incident TB, possibly due to a late TB infection, was reported after completing the 3RH regimen.CONCLUSION: Contact investigation and preventive therapy were successfully implemented in these resource-limited urban settings in programmatic conditions with few additional resources. The 3RH regimen is a valuable alternative to 6H for preventing TB.