Background: Evaluation of the predictive value of diastolic blood pressure; measured by ABPM, for cardiovascular complications in patients with OSA. Methods: This study included 62 patients already diagnosed with Obstructive sleep apnea. All the patients subjected to bedside trans-thoracicechocardiology, ambulatory blood pressure monitoring, resting ECG, Holter 24-hours ECG. Results: There was a positive association between the presence of DM, hypertension, BMI and ‎grades of OSA. ‎SPO2 was lower in patients with severe OSA than mild and moderate cases. ‎ ABPM 24h detected masked hypertension in approximately 45% of included patients. ‎ There was a positive correlation between night-time average diastolic BP and BMI, ‎hypertension, AHI, abnormal‏ ‏IVST, and diastolic dysfunction.‎ Regarding overall detected cardio-vascular complications, diastolic dysfunction was ‎detected in all patients. 65.6% had abnormal IVST, 40.625% had mild tricuspid ‎regurgitation, 18.75% had ischemia and 32.8% had AF. All patients with regional wall ‎motion abnormality had severe OSA. 91.7% of patients with Ischemic changes had ‎severe OSA. ‎Conclusion : ABPM 24h is considered a valuable tool in the detection of masked hypertension in non-dipper OSA patients. OSA is associated with a higher incidence of CVD that increases with increasing degree of OSA.