When the Thai universal coverage (UC) scheme was established, the government decided to exclude renal replacement therapy (RRT) for end-stage renal disease (ESRD) patients from the benefit package, though RRT was included in two other public health insurance schemes. Access to RRT for UC members thus depended on the ability to pay. This study assessed the economic impact of RRT costs on Thai households of different economic status focusing on three issues: (1) the use of RRT; (2) the financial burden of health care payments and (3) household strategies for coping with RRT costs. In-depth case studies of 20 households covered by the UC scheme and having ESRD patients were undertaken using three qualitative data collection approaches: semi-structured and in-depth interviews, and direct observation. Poorer and richer households in urban and rural areas of Nakorn Ratchasima province, a large province in the Northeast where more than 20 per cent of households live below the national poverty line, were purposively selected. The study was conducted in early 2005 and households were visited every 2 weeks for 3 months. Interviews were transcribed and analysed using a thematic approach. The decision to exclude RRT from the UC benefit package created financial barriers to RRT and had a substantial economic impact on poorer ESRD patients. Inadequate dialyses and erythropoietin injections to correct anaemia appeared to be a major cause of death for poorer patients. Household expenditure on RRT took 25–68 per cent of total income or 31–52 per cent of total expenditure, which meant all poorer patients faced catastrophic health spending. In contrast, richer patients had adequate dialyses, resulting in a higher survival rate and quality of life than poorer counterparts. Various coping strategies were employed by poorer patients; these included reducing frequency of dialyses, reducing food consumption, using public transportation to hospitals and taking high interest loans. The RRT cost burden not only impacted patients but also their household members and relatives who provided financial support. Given the two UC policy objectives of equitable access to health care and financial risk protection, the catastrophic impact of RRT costs on poorer households questions the appropriateness of excluding RRT from the UC benefit package. This issue requires further serious attention by the Thai government. Copyright © 2009 John Wiley & Sons, Ltd.