Introduction. Severe acquired brain injury (sABI) is considered the most common cause of death and disability worldwide. sABI patients are supported by their caregivers who often exhibit high rates of psychological distress, mood disorders, and changes in relationship dynamics and family roles. Objectives. To explore lifestyle changes of caregivers of sABI patients during the postacute rehabilitation, by investigating possible differences between primary and secondary caregivers. Primary caregivers spend most of the time with the patient, providing daily care and taking most responsibility for the day-to-day decisions, while secondary caregivers are those who provide additional support. Methods. Three hundred forty-seven caregivers of sABI patients were asked to fill in an unpublished self-report questionnaire to explore their possible lifestyles changes. Results. A statistically significant difference was found between primary and secondary caregivers in time spent in informal caregiving (p<0.001). The primary caregivers reduced all leisure activities compared to secondary carers (p<0.05). Conclusions. By comparing the percentage of leisure activities performed by caregivers beforeand after the patient’s sABI onset, all caregivers showed high percentages of changes in lifestyle and habits, even though primary caregivers reported more negative lifestyle changes than secondary caregivers. Further studies are needed to investigate needs and burden experienced by caregivers of sABI patients during the postacute rehabilitation phase, also in relation to the patients’ outcome, to address support interventions for them and improve their quality of life.