Objective To investigate the correlation between serum levels of folic acid and vitamin B12 and depression. Methods Thirty patients with depression were selected into depression group whose Hamilton de- pression scale score exceeded 17 and/or Hamilton anxiety scale score exceeded 14. Meanwhile, 30 subjects with- out clinically significant depression were selected into control group. Their serum levels of folic acid and vitamin B12 were determined. Zung Self-rating Depression Scale and Self-rating Anxiety Scale were used to evaluate the depression and anxiety. Results The serum levels of folic acid [ (4. 06±1. 61) vs. (6. 48±2. 36) ng/ml, P < 0. 05 ] and vitamin Bl 2 [ (427.96 126. 20) t . (498.46±119.08) pg/ml, P < 0. 05 ] were significantly lower in depression group than those in control group. No correlation was found between Hamilton depression score and serum folic acid level or vitamin B12 leveL Conclusion Patients with depression have lower serum folic acid and vitamin B12 levels than those of the healthy people.