With mood disorders, clinical portrayals alone do not always reflect the exact state and progress of the disease. The present study attempted to evaluate whether changes in regression slope correlating between urinary contents of alpha-1-microglobulin and ulinastatin provided objective information on the severity of mood disorders, based on our previous findings that the regression slope was more steeply inclined in patients with mood disorders than in age-matched healthy subjects. As a result, a close association between scores of the Hamilton Rating Scale for Depression and the regression slopes was found: the more inclined the slope, the greater the severity of symptoms of depression. These results suggest that changes in the slope of the regression plot correlating between urinary contents of alpha 1 M and UT may afford a useful objective index when monitoring the state of patients with mood disorders.