Family members of patients in intensive care units (ICUs) are at risk for mental health morbidity both during and after a patient's ICU stay. To determine prevalences of and factors associated with anxiety, depression, posttraumatic stress and complicated grief in family members of ICU patients. Prospective, longitudinal cohort study. Fifty family members of patients in ICUs at a large university hospital participated. We used the Control Preferences Scale to determine participants' role preferences for surrogate decision-making. We used the Hospital Anxiety and Depression Scale, Impact of Event Scale, and Inventory of Complicated Grief to measure anxiety and depression (at enrollment, 1 month, 6 months), posttraumatic stress (6 months), and complicated grief (6 months). We interviewed all 50 participants at enrollment, 39 (78%) at 1 month, and 34 (68%) at 6 months. At the three time points, anxiety was present in 42% (95% CI, 29-56%), 21% (95% CI, 10-35%), and 15% (95% CI, 6-29%) of participants. Depression was present in 16% (95% CI, 8-28%), 8% (95% CI, 2-19%), and 6% (95% CI, 1-18%). At 6 months, 35% (95% CI, 21-52%) of participants had posttraumatic stress. Of the 38% who were bereaved, 46% (95% CI, 22-71%) had complicated grief. Posttraumatic stress was not more common in bereaved than nonbereaved participants, and neither posttraumatic stress nor complicated grief was associated with decision-making role preference or with anxiety or depression during the patient's ICU stay. Symptoms of anxiety and depression diminished over time, but both bereaved and nonbereaved participants had high rates of posttraumatic stress and complicated grief. Family members should be assessed for posttraumatic stress and complicated grief.