To determine the incidence of primary caregiver burden in a cohort of family members of critically ill patients admitted to ICU and to identify risk factors related to its development in both the patient and the family member. Prospective observational cohort study was conducted for 24 months. Hospital Universitario Clínico San Cecilio, Granada. The sample was the primary caregivers of all patients with risk factors for development of PICS (Post-Intensive Care Syndrome). The follow-up protocol consisted of evaluation 3 months after discharge from the ICU in a specific consultation. The scales used in patients were Barthel, SF-12, HADS, Pfeiffer, IES-6 and in relatives the Apgar and Zarit. A total of 93 patients and caregivers were included in the follow-up. 15 relatives did not complete the follow-up questionnaires and were excluded from the study. The incidence of PICS-F (Family Post Intensive Care Syndrome) defined by the presence of primary caregiver burden in our cohort of patients is 34.6% (n=27), 95% CI 25.0-45.7. The risk factors for the development of caregiver burden are the presence of physical impairment, anxiety or post-traumatic stress in the patient, with no relationship found with the characteristics studied in the family member. One out of 3 relatives of patients with risk factors for the development of PICS presents at 3 months caregiver burden. This is related to factors dependent on the patient's state of health.