Literature suggests that parental cancer can provoke aversive emotional arousal in adult children, who may perceive caregiving as a traumatic experience. Limited research has been conducted on emotional and physiological impact of family caregiving for cancer patients undergoing chemotherapy. The aim of the present study was to examine psychological and physiological responses in parental cancer's caregivers. Two matched groups of adult children, with 78 participants each (parental cancer vs. control), completed psychological measures of distress, post-traumatic stress disorder (PTSD) symptoms, and burden. Additionally, each participant visualised standardised pictures with different emotional valences, while cardiovascular (heart rate) and electrodermal responses (skin conductance) were recorded. Between-group analysis showed significant differences on all psychological variables, and on skin conductance for all types of pictures. However, for the heart rate responses, differences were found only for pictures with unpleasant emotional arousal. In the parental cancer group, the heart rate peak response stood out as a predictor of PTSD symptoms, after controlling for distress and burden. This study highlights the important role of psychophysiological measures of family caregiving in oncology. Physiological responses may explain a higher prevalence of PTSD symptoms. Therefore, biofeedback combined with targeted psychosocial interventions for relaxation could be of great clinical value for this population.