OBJECTIVES: Studies have shown impaired cognitive function after ICU discharge. We aimed to describe long-term cognitive function in Danish ICU patients. DESIGN: Prospective cohort study. SETTING: Single-center ICU at Zealand University Hospital, Køge, Denmark. PATIENTS: Adult patients admitted for over 24 hours. INTERVENTION: Three and 12 months after discharge, the patients were visited at home and tested with the Repeatable Battery for the Assessment of Neuropsychological Status. MEASUREMENTS AND MAIN RESULTS: We included 161 patients, 79 patients had a 3-month and 53 a 12-month follow-up visit. The primary reasons for not being visited at 3-month were death (44 patients), decline (26 patients), or transferal to another ICU (6 patients). Visited patients were median 67 years old (interquartile range, 59-73), had a median Acute Physiology and Chronic Health Evaluation score of 20 (interquartile range, 16-26), 58% were on a ventilator, and 30% were surgical patients. The mean Repeatable Battery for the Assessment of Neuropsychological Status score was 67 (SD, 21), compared with a normal value of 100 (15). A total of 57% had Repeatable Battery for the Assessment of Neuropsychological Status scores corresponding to moderate traumatic brain injury, 46% scored corresponding to light Alzheimer's disease, and 73% corresponding to mild cognitive impairment. After 12 months, the Repeatable Battery for the Assessment of Neuropsychological Status was still reduced (71 ). We examined protective and risk factors using multiple linear regression and found protective effects of being employed before admission (p = 0.0005) or being admitted from a surgical ward (p = 0.019). CONCLUSIONS: In this prospective cohort study of Danish ICU patients, we found significantly reduced cognitive function for intensive care patients 3 and 12 months after discharge.