['Although chest radiography is quick and inexpensive, previous research suggests that it is often misleading in emergency department (ED) patients with decompensated heart failure, resulting in misdiagnosis and inappropriate treatment. This study determines the rate of negative chest radiography results in patients found to have disease and the potential contribution of negative findings to a diagnosis discordant with heart failure by an emergency physician.', 'We used data from the Acute Decompensated Heart Failure National Registry (ADHERE), a registry of patients with a primary hospital discharge diagnosis of heart failure. We compared initial ED admitting diagnosis to the criterion standard of a hospital discharge diagnosis of heart failure and related these to radiographic findings of heart failure (interstitial edema, pulmonary edema, or vascular congestion, as determined by a staff radiologist) for patients first treated in the ED. The proportion of patients with a non-heart failure ED diagnosis and the diagnostic sensitivity of radiographic findings of heart failure are calculated.', 'There were 85,376 patients with chest radiograph results and an ED admitting diagnosis. Overall, there were 15,937 patients with no signs of congestion on ED chest radiography, giving a negative rate of 18.7% (95% confidence interval [CI] 18.4% to 18.9%). The proportion of patients with an ED non-heart failure admitting diagnosis was higher in patients with a negative chest radiograph result (23.3%; 95% CI 22.6% to 23.9%) than in patients with a positive chest radiograph result (13.0%; 95% CI 12.7% to 13.2%).'] Does prevalence of negative chest radiography result in the emergency department patient with decompensated heart failure?