OBJECTIVES: To estimate the amount of government health budget required for the extension of access to renal replacement therapy (RRT) towards beneficiaries of the universal health care coverage (UC) scheme in Thailand. Ability of the government to bear the increasing budget and appropriate measures to cope with anticipated costs of including RRT in the benefit package were also investigated. METHODS: Literature review on demand for RRT at both domestic and international levels, and the estimate of costs for haemodialysis and continuous peritoneal dialysis in Thailand. From the government perspective, several scenarios of budget requirements according to the estimated costs for RRT and possible rationing criteria were calculated. RESULTS: The government would spend approximately more than five billion Baht during the first year of implementation, if there is neither strategy to reduce the costs for RRT nor appropriate selection criteria for end-stage renal disease patients. The budget for universal access to RRT would increase to 74,355 million Baht in the sixteenth year of implementation if the government played passive roles in controlling costs of the program. The budget required would reduce to 58% of the estimate if the government introduced the rationing criteria for patients aged less than 60 years. CONCLUSIONS: The policy on the extension of access to RRT should be considered carefully by the government because of its financial impact on the government health budget. Appropriate interventions including effective measures to control costs of RRT, strategies to reduce the incidence of end-stage renal disease, and the rationing criteria for access to RRT are needed if the decision to implement the policy is made.