RationaleClinical trials of interventions aimed at the families of intensive care unit (ICU) patients have proliferated but recruitment for these trials can be challenging.ObjectivesTo evaluate a strategy for recruiting families of patients currently being treated in an ICU using limited human resources and time-varying daily screening over 7 consecutive daysMethodsWe screened the Johns Hopkins Hospital medical ICU census 7 days per week to identify eligible family members. We then made daily, in-person attempts to enroll eligible families during a time-varying 2-hour enrollment period until families declined participation, consented, or were no longer eligible.Measurements and main resultsThe primary outcome was the proportion of eligible patients for whom ≥1 family member was enrolled. Secondary outcomes included enrollment of legal healthcare proxies, the consent rate among families approached for enrollment, and success rates for recruiting at different times during the day and week. Among 284 eligible patients, 108 (38%, 95% CI 32%-44%) had ≥1 family member enrolled, and 75 (26%, 95% CI 21%-32%) had their legal healthcare proxy enrolled. Among 117 family members asked to participate, 108 (92%, 95% CI 86%-96%) were enrolled. Patients with versus without an enrolled proxy were more likely to be white (44% vs. 30%, P = .02), live in a zip code with a median income of ≥$100,000 (15% vs. 5%, P = .01), be mechanically ventilated (63% vs. 47%, P = .01), die in the ICU (19% vs. 9%, P = .03), and to have longer ICU stays (median 5.0 vs. 1.8 days, P<.001). Day of the week and time of day were not associated with family presence in the ICU or consent rate.ConclusionsFamily members were recruited for more than one third of eligible patients, and >90% of approached consented to participate. There are important demographic differences between patients with vs without an enrolled family member.