Obstructive sleep apnea is a common disorder that is often unrecognized and underappreciated. Emerging evidence suggests that there is a causal link between obstructive sleep apnea and hypertension. This relationship appears to be independent of other comorbidities that have been previously linked to hypertension, such as obesity. The majority of studies support the contention that alleviation of sleep disordered breathing has a clinically significant beneficial impact on decreasing both nighttime and daytime blood pressure. A pathophysiologic basis for patients with sleep apnea having an increased risk for hypertension is not fully elucidated. However, there is consistent evidence that autonomic mechanisms are implicated. Sympathetic activation along with humoral responses to repetitive episodes of hypoxemia and apnea over the longer term may cause vasoconstriction, endothelial dysfunction, and possibly hypertension. Patients with sleep apnea are often obese and may be predisposed to weight gain. Hence, obesity may further contribute to hypertension in this patient population.