There is an increased prevalence of essential hypertension among patients of obstructive sleep apnea. We investigated 50 patients with OSA. They were divided according to their level of blood pressure into group I (Normotensive patients) and group II (hypertensive patients). High blood pressure was found in 40 patients (80%) of the total sample. There was significant increase in the level of mean SBP and DBP at night in all groups over the normal levels and increase in the level of the mean SBP and DBP in the total sample and in group II,but not in group I. There was significant decrease in the maximum and mean BP in the second night and day after correction of the apnea using the CPAP therapy, compared to first night and first day before treatment.Conclusion: OSA increase both the nocturnal and day-time mean BP. There is marked reduction in the level of the BP in the hypertensive and Normotensive groups after correction of the obstructive sleep apnea by normal CPAP.