Background: Long term high blood pressure is a major risk factor for coronary artery disease, stroke, heart failure, peripheral vascular disease, vision loss and chronic kidney disease. Objective: To demonstrate the relation between left ventricular diastolic dysfunction increased left ventricular mass and ambulatory blood pressure recording in subjects not known to be hypertensive. Patients and Methods: This was a- cross sectional study that carried out on (100) normotensive patients in Cardiology Department Clinic at Matrouh Specialized Cardiothoracic and Interventional Catheterization Center from October, 2017 to January 2019. Results: there was a-significantly marked difference in left ventricular (LV) mass between two groups (normal blood pressure and latent hypertension) and significantly marked difference in diastolic dysfunction. According to normal circadian and impaired circadian, there was a- significant difference between the two major groups in sex, where male >female, and marked difference in LV mass between the two groups (normal circadian and impaired circadian), and in smoking. Conclusion: Ambulatory blood pressure (AMBP) played an important role as a predictor to estimate prevalence of hypertension based on diastolic dysfunction and increased left ventricular mass in persons with normal blood pressure measures at office specially masked hypertension in white coat hypertensive patients.