Objective: Early recognition of left ventricular hypertrophy is important because antihypertensive treatment decreases morbidity and mortality. The ideal screening method for left ventricular hypertrophy in hypertensive emergency department (ED) patients has not been identified. Our objective was to determine the diagnostic accuracies of electrocardiogram (ECG) and N-terminal Pro-B-type natriuretic peptide (pro-BNP) for left ventricular hypertrophy individually and in combination in hypertensive ED patients. Methods: Prospective diagnostic study in an academic urban tertiary care hospital ED with annual census of 65 000 visits. Inclusion criteria are as follows: adult ED patients with systolic blood pressure greater than or equal to 160 mm Hg or diastolic blood pressure greater than or equal to 100 mm Hg on 2 or more measurements taken 60 minutes apart. Exclusion criteria are as follows: patients with heart failure, renal insufficiency/failure, acute myocardial infarction, or without recent or scheduled echocardiograms. All patients received echocardiograms and had pro-BNP levels measured using a RAMP point-of-care device (Response Biomedical, Vancouver, BC, Canada). We calculated diagnostic test characteristics with 95% confidence intervals (CIs). Results: A total of 49 patients were enrolled. The average age was 57.9 years, 26.5% were male, and 63.3% were African American. Thirty-two patients (65%) had left ventricular hypertrophy by echocardiogram. Twenty-one (43%) had ECG evidence of left ventricular hypertrophy. Median pro-BNP level was 268 pg/mL. The combination of the 2 tests provided the greatest specificity (94%; 95% CI, 69%-99.7%) and positive predictive value (94%; 95% CI, (68%-99.7%). Conclusions: The combination of ECG and pro-BNP is a promising screening algorithm for identification of hypertensive ED patients with left ventricular hypertrophy.