OBJECTIVE Hypoalbuminemia has been reported in patients with severe disability and epilepsy and in patients with epilepsy treated with short-term sodium valproate (VPA) therapy; however, serum albumin concentrations have not previously been determined in otherwise healthy patients with epilepsy and receiving long-term VPA monotherapy. METHODS Serum albumin concentrations were determined in 26 ambulatory children with epilepsy before and at 6, 12, and 24 months of VPA monotherapy. Serum total protein concentrations and serum concentrations of other biochemical markers of liver and renal function such as alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltransferase, and creatinine concentration were also measured in the study participants before and at 6, 12, and 24 months of treatment. RESULTS Serum albumin concentrations were reduced at 6 months of treatment (P = 0.007). Serum alanine aminotransferase concentrations were significantly increased at 6 (P = 0.034) and 12 months of treatment (P = 0.046), whereas serum aspartate aminotransferase concentrations were significantly increased at 6 (P = 0.002) and 12 months of treatment (P = 0.002). There were no significant correlations between serum albumin and the other parameters at 6 months of treatment. CONCLUSIONS Ambulatory children who receive VPA monotherapy may have early but transient decrease in serum albumin concentrations. Further studies are needed to address this issue and to determine the possible clinical implications and the mechanisms involved in VPA-mediated decrease in serum albumin concentrations.