OBJECTIVE: To study the effects of topiramate (TPM) and valproate acid (VPA) on serum insulin and leptin levels in young and adult rats. METHODS: Thirty healthy female young rats (21 days old) and thirty healthy female adult rats (2 months old) were randomly administered with TPM (50 mg/kg daily), VPA (200 mg/kg daily) or normal saline (control group) by intragastric administration for 5 weeks. After 5 weeks, serum leptin and insulin levels were detected by radioimmunoassay (RIA). RESULTS: Serum leptin and insulin levels in both the young and adult TPM groups were remarkably lower than those of the corresponding control group (P<0.05). The adult TPM group had significantly lower serum leptin and insulin levels than the young TPM group (P<0.05). In contrast, serum leptin and insulin levels in both the young and adult VPA groups were remarkably higher than those of the corresponding control group (P<0.05). The young TPM group had significantly higher serum leptin and insulin levels than the adult TPM group (P<0.05). CONCLUSIONS: TPM decreases serum leptin and insulin levels in young and adult rats, especially in adult rats. VPA increases serum levels of both in young and adult rats, especially in young rats.［Chin J Contemp Pediatr, 2007, 9 (3):229-232］