A cluster-randomized crossover trial involving adult ICU patients, family members and ICU workers is being conducted. Near 35 intensive care units (ICUs) will be evaluated. In the first study period (T1) Brazilian ICUs with RFVMs (<4.5 hours/day) will be randomly assigned to either an restrictive family visitation model (RFVM) (intermittent visits according to local ICU regulation) or to a flexible family visitation model (FFVM) (12 consecutive hours per day) in a 1:1 ratio. After enrollment of 25 patients and 25 family members, there will be a 30-day period without subject recruitment (T2) to avoid contamination bias. After this period, each ICU will be assigned to an intervention contrary to that which initially receive (T3) until the enrollment of more 25 patients and 25 family members. The primary outcome is the cumulative incidence of delirium among ICU patients. Secondary outcome measures include delirium-free days, mechanical ventilation-free days, any ICU-acquired infections, ICU length of stay and all-cause hospital mortality among patients; satisfaction and symptoms of anxiety and depression among family members; and prevalence of symptoms of burnout syndrome among ICU workers. Tertiary outcomes include need of antipsychotic use, need of mechanical restraints, unplanned loss of invasive devices, and ICU acquired pneumonia, urinary tract infection and bloodstream infection among ICU patients; perception of involvement in patient care among family members of ICU patients; and satisfaction among ICU workers.