Objective To explore the diagnostic value of sympathetic skin response ( SSR) and P300 event-related potentials (ERP) in depression patients. Methods The SSRs and ERPs of 46 depressed patients and 42 normal healthy people were measured. Results Abnormal rates of SSR were observed in 84. 8% of the depressed group (39/46) and 78.3% (36/46) of the controls. Compared with those in the control group, the latency and amplitude of the SSRs were significantly longer and lower in the depressed group. Abnormal ERPs were observed in 89. 1% of the depressed group(41/46) compared with 78. 3% of the controls (36/46). The latency of N2 and P3 and the amplitude of P3 in the ERPs of the depressed patients were longer and lower in comparison with those in the control group. Hence there was a significant difference between two groups. There was a high positive correlation between N2 and P3 latency in the ERPs and the SSR readings in the depressed group, and between amplitude of P3 and SSR, while there was a significant negative correlation between latency and amplitude in the two indexes of P300 and SSR in the depressed group. Conclusion SSR and ERP have remarkable clinical value as diagnostic indexes for depres-