Mediastinal lymphadenopathy is an X-ray syndrome manifested by an increase in lymph nodes. Etiological causes represent a heterogeneous group. One of the new diagnostic methods is transbronchial aspiration biopsy of the mediastinal lymph nodes under the control of endosonography (EBUS-TBNA). Objective. To determine which technological parameters influence on the diagnostic accuracy of EBUS-TBNA in the verification of mediastinal lymphadenopathy. Material and methods. Prospective, non-randomized study. Period: February 2012-February 2020. Inclusion criteria: Short diameter of at least one of the lymph nodes of groups 4R; 7; 4L is equal to or more than 1.0 cm; age equal to or over 18 years old; informed consent in the study. Exclusion criteria: A history of a verified socially significant disease; a positive sputum test for M. tuberculosis microscopy or polymerase chain reaction for tuberculosis (PCR-RT). The study included 235 patients. EBUS-TBNA was performed using an ultrasound bronchoscope (EB-1970UK (Pentax) and an ultrasound scanner (EUB 5000 Plus G OB/GYN-Vascular Ultrasound (HITACHI). Punctures were performed with special 22G transbronchial ultrasound needles. For mathematical processing a method was used-the method of constructing classification trees (CHAID method). Results. Overall sensitivity was 80%. The sensitivity for puncture of 1; 2; 3 and more groups was 65%: 83%: 85%, respectively. When using an active aspiration-84%. Conclusion. Factors that increase the sensitivity of EBUS-TBNA in order to verify mediastinal lymphadenopathy are biopsy of 2 or more groups of mediastinal lymph nodes and the use of active aspiration.