We systematically reviewed the literature to ascertain how well clinicians determine the probability and type of left-sided heart failure in their patients. Left-sided heart failure is characterized by decreased left ventricular ejection fraction or increased filling pressure. The type of heart failure determines optimal treatment. Systolic dysfunction exists when ejection fraction is reduced. Diastolic dysfunction is presumed to be present when filling pressure is increased with a normal ejection fraction and without another explanatory diagnosis. Many findings are associated with heart failure, and wide variation exists in clinicians' ability to detect these findings. The best findings for detecting increased filling pressure are jugular venous distention and radiographic redistribution. The best findings for detecting systolic dysfunction are abnormal apical impulse, radiographic cardiomegaly, and q waves or left bundle branch block on an electrocardiogram. Diastolic dysfunction is especially difficult to diagnose, but is associated with an elevated blood pressure during heart failure.