Serum albumin (sALB) is routinely determined in blood tests and is an excellent predictor of risk for many medical illnesses. Hypoalbuminemia has been sporadically reported in patients with psychiatric disorders, such as major depressive disorder and schizophrenia. We compared sALB levels between 19 drug-free patients of major depressive disorder with a control group of matching diets. We conducted this study by controlling the nutrition factor by assessing patient's diets, as well as other possible confounding factors such as sex, age, body mass index (BMI), liver function, and exercise, while focusing on hypoalbuminemia in patients with major depressive disorder. There is no difference in age, gender distribution, and dietary frequency on protein and albumin intake between the patient and control group. The sALB levels of the group with major depressive disorder were significantly reduced (p=0.049). The severity of depression is negatively correlated to the sALB level (r=-0.46, p=0.04). Hypoalbuminemia has clinical meanings on severity of depression and is independent of malnutrition. However, our results can only be seen as very preliminary and should be confirmed by larger studies.