OBJECTIVES: The purpose of this study was to determine the relationship between depression and heart rate variability (HRV) in rehabilitation ward inpatients. METHODS: Depression was assessed using the Self-Rating Depression Scale (SDS) in 10 inpatients in a convalescent rehabilitation ward. We also measured R-R intervals during nighttime rest, evaluated HRV by frequency analysis, and confirmed the association between autonomic activity and depression by calculation of Spearman\'s rank correlation coefficient. RESULTS: A negative correlation was found between depression and the very low-frequency (VLF) band of HRV (rho=-0.70, P<0.05). SDS showed no significant correlation with low-frequency (LF) band (rho=-0.32, P=0.36) or high-frequency (HF) band (rho=-0.21, P=0.46). CONCLUSIONS: The results of this study suggest that the VLF band of HRV may be an effective indicator of autonomic activity in the evaluation of depression. Further studies are needed to verify the usefulness of the VLF band of HRV as an indicator for detecting depression.