Urban residents in India face important health problems due to unhygienic conditions, excessive crowding and lack of proper sanitation. The private sector has started occupying the centre stage of the health system and households are burdened with increasing levels of health expenditure. This paper aims to study out-of-pocket expenditure (OOPE) and the extent of catastrophic payments for health care among households in a highly urbanised state, Tamil Nadu. The study used data on morbidity and health care for the year 2004 collected by the National Sample Survey Organization, India. Care was sought for 84 per cent of illness episodes in urban areas, and the majority used private sector providers (67 per cent for inpatients and 78 per cent for outpatients). Mean OOPE for inpatients and outpatients was higher for households with higher income. The average cost burden per visit was higher among those who sought care from private providers for inpatient services (29 per cent of household consumption expenditure) and outpatient services (20% of household consumption expenditure) compared with the burden associated with public health service use (3–4 per cent of consumption expenditure). About 60 per cent of households which used private health services faced catastrophic payments at the 10 per cent threshold level. To avoid catastrophic expenditure, greater use of the public sector which is providing services at an affordable cost is needed. Improving access to public health services, better gate-keeping systems, stronger controls on drug prices and increasing the quality of services are required to reduce the incidence of catastrophic expenditure both on inpatients and outpatients. Greater use of risk pooling mechanisms would encourage the poor to seek health care and also to protect households from all socio-economic groups from catastrophic expenditure. Copyright © 2009 John Wiley & Sons, Ltd.