Objective: To assess obstructive sleep apnea impact on the target blood pressure (BP) value achievement in non-obese hypertensive patients. Design and method: In this prospective cross-sectional study were included 305 patients (mean age 60.0 years old [48.0; 67.0], 203 men) with different stages and grades of arterial hypertension (AH). All patients have been receiving antihypertension therapy, prescribed by their cardiologist, for at least 3 weeks before inclusion in the study. During the study, office systolic and dyastolic blood pressure (SBP and DBP resp.) were assessed (oscillometric method, Omron, Japan) and home sleep respiratory monitoring (SomnoChek, Weinmann, Germany) was done in all patients. Results: Two groups were formed: non-target BP group (BP>140/90 mm Hg, n=164) and target BP group (BP<140/90 mm Hg, n=141). Comparative data analysis included such indicators as: age, body mass index (BMI), apnea/hypopnea index (AHI), desaturation index (DI) and minimum oxygen saturation (min SaO2), revealed only differences between age (61.0 years old [50.0; 68.0] versus 57.0 years old [47.0; 66.0] resp., p=0.03) and BMI (32.5 kg/m2 [29.7; 38.1] vs. 31.6 kg/m2 [27.8; 35.5] resp., p=0.02). The analysis of non-obese patients’ data (BMI <30 kg/m2, n=100) didn’t reveal differences by age, but a higher value of AHI and DI were determined in patients with non-target BP, as well as higher BMI; similar differences were not found in obese patients (BMI>30 kg/m2, n=205) (Table 1). In two-factor logistic regression analysis (included AHI and BMI) AHI was the only predictor of non-target BP in patients without obesity, while BMI had no predictive value (Table 2). Conclusions: Even mild or moderate obstructive sleep apnea may be an important negative factor in achieving BP targets in non-obese patients, unlike the other clinical cases with AH.