This case–control study compares the health of Thai family caregivers of adults with acquired physical disabilities with others without similar responsibilities. To ascertain health perceptions, face-to-face structured interviews using the Short Form (36) were conducted with participants randomly selected from primary care units in eastern Thailand (150 in each group). Despite similar sociodemographic profiles, caregivers reported more health problems and harmful health behaviours. Mean scores for physical and mental health were significantly lower. Factors contributing to poorer health among both caregivers and controls were older age, low educational level, insufficient income and existing health problems. Additional factors for caregivers were gender, spousal or in-law relationship, high dependency, long caregiving time, lack of previous experience and other caregiving responsibilities. This study identifies an urgent need for support to promote caregivers' health to enable them to maintain their vital role.