Introduction: Guidelines suggest suspecting obstructive apnea-hypopnea syndrome (OSA) in patients with hypertension (HT) if the nocturnal blood pressure is elevated, a patient is a non-dipper or an inverse pressure pattern is observed. The objective of our work is to describe the behavior of blood pressure by ambulatory blood pressure monitoring (ABPM) in patients with OSA and HT who do not receive pharmacological treatment and CPAP. Materials and Methods: It is a retrospective study in adults, including patients with HT and OSA without antihypertensive treatment or CPAP. Epworth Sleepiness Scale (ESS), Berlin and the STOP-BANG (SBQ) questionnaire were checked against home-based respiratory polygraphy (RP) and HT patterns through 24-h outpatient scores ABPM. Results: We analyzed 83 patients of which 42 were men (51%) with a mean age of 44.5 years. 48 (57%) of these patients had nocturnal hypertension (NH); 30 (36%) showed daytime and nocturnal hypertension (DNH), and 5 (6.8%) had just daytime hypertension (DH). OSA clinically relevant were represented by 33.3% in the NH group, 36.6% of patients in the DNH group and 40% in the DH group (p = 0.92). Severe OSA stood for 20.8% in the NH group, 33.3% in the DNH group and 20% in the DH group (p = 0.37). We found no differences in sleepiness symptoms, in oxygen desaturation index (ODI) and desaturation time less than 90% (T < 90%). Conclusion: The diagnosis of OSA in hypertensive patients should be suspected considering different parameters such as clinical presentation, the ABPM values and presence of comorbidities.