Background and Objective: 24-h ambulatory blood pressure monitoring (ABPM) aids to precisely identify patients with true resistant hypertension (tRH). The present study was aimed to assess the frequency and correlates of tRH among patients with clinically suspected RH. Methods: Medical records of treated hypertensive patients referred in four healthcare centers for BP control evaluation by 24-h ABPM were reviewed to assess the prevalence of tRH. Inclusion criteria were age ≥ 18 years, clinical diagnosis of RH. Data on demographic, clinical, laboratory, 2D-echocardiography and 24-h ABPM parameters were retrieved from patient’s medical records. True RH (tRH) was defined as office blood pressure (BP) ≥ 140/90 mmHg and 24-h ambulatory BP ≥ 130/80 mmHg. Simple and multiple linear regression analyses were used to assess factors associated with systolic BP (SBP) as a proxy of RH among patients with tRH. P < 0.05 defined the level of statistical significance. Results: Of 636 patients referred for BP control evaluation by 24-h ABPM, 75 (11.7%) had suspected RH by office BP measurements. After 24-h ABPM, pseudo or apparent RH (aRH) and tRH were observed in 15 (2.3%) and 60 (9.4%) patients, respectively. BMI (p = 0.007) and blood glucose (p = 0.024) were positively associated with SBP whereas a negative association was observed with eGFR (p = 0.022) among tRH hypertensive patients in multiple regression analysis. Conclusion: True RH was a common finding among patients with clinical RH and associated with obesity and silent target organ, especially kidney dysfunction. The present study highlights the diagnostic and prognostic importance of 24-h ABPM among patients with clinical RH.