OBJECTIVE Catatonia is a neuropsychiatric syndrome with motor and behavioral symptoms occurring in patients with or without a history of psychiatric illness. Although it is associated with significant morbidity and mortality, the prevalence of catatonia in the ICU setting is unknown. The diagnosis and management of catatonia in the critically ill patient raises unique challenges. Furthermore, the diagnosis and management are not included in most critical care curricula. The objective of this retrospective study is to increase the awareness of this clinically important condition among critical care providers. DESIGN Retrospective case series study. SETTING Multiple critical care units at a university-affiliated tertiary care hospital. PATIENTS Five critically ill patients with catatonia, aged 17 to 78. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS All notes, laboratory data, imaging results, other diagnostic studies, therapeutic interventions, and responses to treatment were reviewed for five critically ill patients with catatonia. No unifying cause of catatonia or predisposing conditions were identified for these patients. Currently available diagnostic criteria for catatonia were found to be nonspecific in the ICU setting. New diagnostic criteria for catatonia specific to the critically ill patient are proposed. CONCLUSIONS Catatonia can occur in a wide variety of critical care settings, with or without precedent psychiatric illness, and it may be exacerbated or induced by common intensive care practices. Psychomotor findings are imperative in examination of critically ill patients with altered mental status in order to diagnose catatonia.