Objective: To assess the comparative contribution of clinical assessment, electrocardiography, and chest radiography to the diagnosis of left ventricular systolic dysfunction in patients admitted to a general medical ward tiffs acute dyspnoea. Design: Prospective cross sectional study. Setting: Acute medical admissions ward of a teaching hospital. Subjects: 71 randomly selected patients admitted with acute dyspnoea. Main outcome measures: Sensitivity and specificity of each investigation and logistic regression analysis of each variable in identifying left ventricular systolic dysfunction. Results: Clinical assessment in this cohort of patients with severe dyspnoea was generally sensitive (sensitivity 81%). Patients were divided into three groups on the basis of clinical assessment. In the first group (37 patients) the diagnosis of systolic dysfunction was dear, in the second (22) it was in doubt, and in the third (12) it was unlikely. The sensitivity of clinical assessment in identifying left ventricular systolic dysfunction was 81% and the specificity was 47%. The specificity of diagnosis was improved by electrocardiography (69%) and chest radiography (92%). Logistic regression analysis showed that isolated pulmonary crepitations were a comparatively poor predictor of left ventricular systolic dysfunction (?2 = 10.215, P = 0.0014) but that a full clinical examination had reasonable predictive value (?2 = 24.82, P < 0.00001). The combination of clinical assessment and chest radiography improved the accuracy of diagnosis (?2 = 28.08, P < 0.00001), as did the combination of clinical assessment and electrocardiography (?2 = 32.41, P < 0.00001). Conclusion: Clinical assessment in patients admitted with acute dyspnoea is comparatively accurate. Patients with abnormal results on chest radiography, electrocardiography, and clinical examination have a high likelihood of having left ventricular systolic dysfunction. Echocardiography contributes little more to the diagnosis in these patients and may be more efficiently directed towards patients in whom the diagnosis is still in doubt after clinical assessment, chest radiography, and electrocardiography.