The diagnostic utility (sensitivity, specificity, and overall efficiency) of autonomic nervous system measures in distinguishing hospitalized patients with unipolar depression from age-matched normal controls is reported. Tonic resting skin conductance level (SCL), tonic resting heart rate level (HRL), and thephasic skin conductance and heart rate responses (SCRs and HRRs) to task-related stimuli were used. The overall efficiency of SCL of 70% was generally consistent with previous research. The other measures yielded greater efficiency: 80% for SCR, 90% for HRL, and 83% for HRR. The possible role of autonomic measures in the diagnosis of major depressive episodes is discussed.