RATIONALE: The aim of this study was to establish the first ketogenic diet treatment program for refractory epilepsy in Thailand and to assess its feasibility as well as its efficacy. METHOD: Children with refractory epilepsy were enrolled in the study. This was a prospective open trial study with 35 children (16 boys and 19 girls). Not all patients started on the diet at the same time. Each patient was cumulatively enrolled in this study over the period of 4 years. The mean age on diet was 5.37 +/- 3.57 years (2 months-13 years), mean age of onset of seizures was 19.2 +/- 27.47 months (1 days-8 years), and an average duration on ketogenic diet was 7.67 months (6 days to 29 months). The classic "4:1" formula ketogenic diet was used with some modification. The patient's parents were allowed to improvise and use any fatty diets available in the market such as coconut milk if needed. Parents were closely supervised and instructed on how to prepare the patient's own meals while in the hospital and continued to attend neurology and nutrition clinics. The seizure outcome and side effects were monitored as well as a daily test for urine ketone. RESULTS: At 1 month, 3 months, 6 months, and 12 months duration on the diet, 90 per cent seizure reductions were achieved in 62.5 per cent, 68.18 per cent, 75 per cent, and 66.67 per cent of patients remaining on the diet, respectively. The number of antiepileptic drugs (AEDs) used by each patient also decreased as a result of better seizure control. CONCLUSION: Ketogenic diet can be tried as a management option for refractory epilepsy. It is not difficult to implement even in a developing country like Thailand where resources are limited. It may also help reduce the cost of treatment especially in view of the high prices of the new AEDs.