Adverse social conditions and social habits are significant as a cause of illness because of their power to disable. Chronic infections like TB present some of the most serious medical social problems put a heavy emotional strain on the patient. A TB control programme can be effective when the causal factors in adverse social conditions such as poverty, undernourishment and social habits are removed. The medical social worker, by working with the doctor and helping to co-ordinate services of the social and health agencies, can play an important role in the control of TB.