OBJECTIVE: To investigate the distribution and frequency of UGTIA6 A541G genetic polymorphism in Han epileptic children from Henan and to evaluate the effect of UGTIA6 A541G genetic polymorphism on serum concentrations of valproic acid. METHODS: The method of gas chromatography was used to assay serum concentrations of valproic acid. UGTIA6 A541G genetic polymorphism was screened by PCR-RFLP. Direct sequencing was used to confirm the expected sequences of each genotype. RESULTS: The genotypic frequencies of UGTIA6 A541G were as follows: AA in 76 cases, AG in 65 cases and GG in 6 cases. The mean values of serum concentrations of valproic acid in patients with A541G AA, AG and GG were 3.91±1.57, 3.59±1.39 and 3.73±1.28 μg/mL, respectively (dose-adjusted trough concentration on a mg/kg basis). There were no significant differences in serum concentrations of valproic acid among the three groups. CONCLUSIONS: UGT1A6 A541G gene polymorphism does not influence serum concentrations of valproic acid in Han epileptic children. Individual differences in serum concentrations of valproic acid may be attributed to many factors.［Chin J Contemp Pediatr, 2010, 12 (6):429-432］