Acute left ventricular (LV) dysfunction is common in the critical care setting and more frequently affects the elderly and patients with comorbidities. Because of increased mortality and the potential for significant improvement with early revascularization, the practitioner must first consider acute coronary syndrome. However, variants of stress (takotsubo) cardiomyopathy may be more prevalent in ICU settings than previously recognized. Early diagnosis is important to direct treatment of complications of stress cardiomyopathy, such as dynamic LV outflow tract obstruction, heart failure, and arrhythmias. Global LV dysfunction occurs in the critically ill because of the cardio-depressant effect of inflammatory mediators and endotoxins in septic shock as well as direct catecholamine toxicity. Tachycardia, hypertension, and severe metabolic abnormalities can independently cause global LV dysfunction, which typically improves with addressing the precipitating factor. Routine troponin testing may help early detection of cardiac injury and biomarkers could have prognostic value independent of prior cardiac disease. Echocardiography is ideally suited to quantify LV dysfunction and determine its most likely cause. LV dysfunction suggests a worse prognosis, but with appropriate therapy outcomes can be optimized.