Introduction. Resistant hypertension (RHT) is recognized when the blood pressure (BP) is equal to or greater than 140/90 mmHg, despite changes in lifestyle and using at least 3 antihypertensive drugs, including diuretics at optimal doses. Often, patients limit the proper control of BP by voluntary reduction and discontinuation of less tolerated drugs, failure to follow healthy lifestyle rules, and taking medications that increase BP. The reason for the lack of effects in treatment of hypertension (HT) is also unrecognized secondary HT. The aim of the study is to evaluate the occurrence of pseudo-RHT in patients with primary RHT diagnosis. Material and methods. The study was conducted in 2012-14 among patients hospitalized in the Department of Cardiology of The Pope John Paul II Province Hospital in Zamość. 99 patients diagnosed with RHT were examined, (59 men) at age 54.5-67.0 on average 60.0 ± 9.8 years. Statistical analysis was performed based on Statistica; Chi2 and U-Mann-Whitney tests were used. Results. The final group consisted of 93 people (55 men). In the course of hospitalization, studies were conducted for secondary causes of HT. Efficacy of treatment was evaluated, education on healthy lifestyle was conducted and in some cases pharmacotherapy was modified. As a result of the diagnostic procedure and increased control of applied therapy, 30 patients with true RHT and 63 patients with pseudo-RHT were identified from a group of 93 patients with initial RHT. Patients with true RHT (16 men) were proposed renal artery denervation. Conclusions. A large group of patients with diagnosed RHT are patients with pseudo-RHT. The common cause of RHT is the presence of an undetected secondary HT.