OBJECTIVE: Long-term used of valproic acid in children with epilepsy is related with the increasing of blood ammonia level caused by carnitin deficiency. This study investigated the effect of carnitin supplementation on blood ammonia level associated valproic acid therapy in children with epilepsy. 
METHOD: A randomized double blind placebo controlled trial on 38 subjects with epilepsy who have been treated with valproic acid for more than 3 months were proceeded at Pediatric Neurologic Clinic, Sanglah General Hospital, Denpasar, Bali. Sixteen subjects were given carnitin supplementation and the others were given placebo during a month. The blood ammonia level was compared between groups. Independent t-test was used to analysis the mean difference between groups with significancy if P value < 0.05. Mean difference and 95% confidence interval were also calculated.
RESULT: The study including 50% male with mean age 77.5 months. Epilepsy duration was 37.5 months and duration of valproic acid treatment was 29.5 months. Blood ammonia level in subjects who received carnitine supplementation and placebo was 44.6 (SD 23.2) ?g/dL and 73.5 (SD 40.7) ?g/dL, respectively (p = 0.015). Mean difference of ammonia level between groups was 28.8 ?g/dL and 95%CI was 5.8 to 51.9 ?g/dL. 
CONCLUSION: Subjects with epilepsy who have been treated with valproic acid for more than 3 months and received carnitin supplementation significantly have lower blood ammonia level.