Abstract: OBJECTIVE To explore the relationship between serum concentration and clinical efficacy of valproic acid in the treatment of patients with mania. METHODS Sixty patients of mania were divided into two equal number groups, the treatment group was given depakine chrono (1 000 mg·d-1) and the control group was given magnesium valproate (1 000～1 200 mg·d-1 )for 6 weeks. At the 1st, 2nd, 4th and 6th weekends of treatment, the serum concentration of valproic acid were determined with HPLC and the clinical efficacy were assessed with the BRMS and TESS. RESULTS The response rates were 80% in treatment group and 76.67% in control group. There was no significant difference（P>0.05）.The serum concentration averaged （77.58 ±14.45） μg·mL-1,the therapeutic window was 50-100 μg·mL-1.CONCLUSION The results suggest that it is effective of valproic acid in treatment of mania.The clinical efficacy was related to its serum concentration. It is helpful to monitoring serum concentration of valproic acid in treatment of mania