Background: Many family caregivers of patients with cancer feel guilty about self-care. A meaningful relationship with patients reduces such negative feelings and functions as self-care for family caregivers. Moreover, handholding improves autonomic functions in non-cancer patients. However, the effects of handholding on both patients with cancer and family caregivers remain unknown. Methods: We evaluated the effects of handholding on heart rate variability (HRV) in patients with cancer and their family caregivers.