Background It is debated whether echocardiography should be part of the diagnostic workup in all hypertensive patients. We identified some factors potentially associated with left ventricular hypertrophy (LVH) at echocardiography in untreated hypertensive patients. Methods and Results We studied 2150 patients without LVH at ECG. All patients underwent standard 12-lead ECG and echocardiography. Mean age was 48.7 years, and mean office blood pressure was 154/97 mm Hg. Prevalence of echocardiographic LVH (LV mass >47.0 g/m2.7 in women and >50.0 g/m2.7 in men) was 37.1%. We developed a nomogram based on 7 items (age, smoking, body mass index, office systolic and diastolic blood pressure, Cornell voltage, and chronic kidney disease) on the basis of a multivariable logistic regression analysis. We internally validated the model by bootstrap recalibration and obtained a calibration curve to assess agreement in the validation data set. Probability of LVH at echocardiography ranged from <10% (score, ≤100 points) to >90% (score, ≥180 points). Proportion of patients with LVH progressively increased with the total score (χ2=444.8; P<0.001). Prevalence of LVH was <2% and 90% at the lower 5th and upper 95th percentile of its distribution, respectively. Conclusions We developed and validated a novel score to assess the probability of LVH at echocardiography in hypertensive patients without LVH at ECG. The score may guide the appropriateness of echocardiographic study in low-risk hypertensive patients. Echocardiography appears most appropriate for score values >136 in men and >124 in women.