The ability of the Hamilton Psychiatric Rating Scale for Depression (HRSD) and the Hamilton Anxiety Rating Scale (HARS) to discriminate major depressive disorder (MDD) from generalized anxiety disorder (GAD) was studied in 120 psychiatric outpatients and cross-validated with another 71 outpatients. Factor and discriminant analyses were used to develop revised anxiety and depression scales that were less positively correlated with each other, showed greater internal consistency, and differentiated MDD and GAD better than the original scales. The recombined scales also displayed higher rates of correctly assigning the samples to these disorders than did the original scales.