The aims of the study were twofold. First, the study examined the extent to which there are gender differences in the experience of caring in a sample of relatives of patients with serious mental illness. Secondly, the study examined the association of self-reports of health and functioning with the experience of burden among relatives of patients with serious mental illness. A total of 50 relatives of 32 patients receiving psychiatric treatment for their bipolar or psychotic condition completed the Experience of Caregiving Inventory (ECI) and COOP-WONCA (a self-report measure of general state of health and functioning). The study revealed that female relatives had a higher score on eight of 10 ECI subscores, and in both ECI negative and ECI positive. Additionally, the study revealed significant correlations between a higher score on the COOP-WONCA feeling subscore and the following ECI subscores: stigma (r = 0.304, p < 0.05), problem with services (r = 0.348, p < 0.05), need to back up (r = 0.335, p < 0.05), loss (r = 0.293, p < 0.05) and the total ECI negative subscore (r = 0.343, p < 0.05). We also found a significant correlation between a higher score on the overall health subscore (COOP-WONCA) and a higher score on problems with services (r = 0.290, p < 0.05). Gender was the strongest predictor of the ECI negative subscore. Neither the COOP-WONCA subscore physical health, daily activities or social activities correlated significantly with any of the ECI subscores. Our results showed strong associations between poor mental well-being and caregiver burden. We also found a higher association with gender and the feelings subscore (COOP-WONCA) on ECI negative than we had expected.