Although hypertension (HTN), obstructive sleep apnea (USA), and obesity frequently co-occur, the precise role of obesity in this interrelationship is not completely understood. A total of 727 USA patients were assigned to body mass index (BMI) <25 (27.6%; n = 201), 25 <= BMI <29.99 (53.4%; n = 388), and BMI >= 30 (19%; n = 138). HTN risk factors in each group were evaluated. A total of 244 (33.6%) patients exhibited co-morbid HTN, of whom 20.5% (50/244), 52.9% (129/244), and 26.6% (65/244) were distributed between the BMI <25, 25 <= BMI <29.99, and BMI >= 30 groups, respectively. Multiple logistic regression indicated that age, male gender, triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and apnea-hypopnea index (AHI) scores were HTN risk factors for the BMI<25 group. In the 25 <= BMI <29.99 group, risk factors were age, BMI, diabetes, and AHI. Finally, in the BMI >= 30 group, risk factors were age, diabetes, TG, LDL-C and AHI. These results demonstrate that different risk factor panels were associated with HTN in USA patients with different BMIs. 2015 American Society of Hypertension. All rights reserved.