Objective: to evaluate effectiveness of etiological verification of pulmonary mycobacteriosis (PM) in patients with diagnosed “pulmonary TB without bacteriological or histological confirmation” (А16.0) as per ICD-10 and species diversity of nontuberculous mycobacteria (NTM) in resection samples from the studied cohort. Materials and methods.We analyzed test results from 28 patients with initially diagnosed “pulmonary TB without bacteriological or histological confirmation” (А16.0) as per ICD-10 and verified PM according to resection sample studies. The microbiological study (at least two sputum samples, one bronchobiopsy sample, and one resection sample) included luminescent microscopy (LUM), extraction of M. tuberculosis DNA or NTM DNA by polymerase chain reaction (PCR), culture growth on liquid media in the ВАСТЕС MGIT 960 system, identification of mycobacteria by molecular genetic methods: real-time PCR for M. tuberculosis DNA detection (Syntol, Russia) and DNA-strip technology (GenoType Mycobacterium CM/AS Hain Lifescience). Results. The analysis of referral diagnoses established that in more than half of patients with diagnosed “pulmonary TB without bacteriological or histological confirmation” (А16.0) changes in the lungs had been referred to tuberculoma (64.3%) or infiltrative TB (21.4%); 28.6% of patients had received TB treatment as per chemotherapy regimen no. 3, and 17.8% of patients – broad-spectrum antibiotics. TB treatment duration varied from 4 to 28 months. Atypical lung resections were performed in most cases (75%). NTM DNA detection in resection samples was the most informative method of etiological verification of PMB (100% of cases). NTM culture growth was observed in 17.9% of cases. Only slowly-growing NTM were represented in the studied cohort as etiologically significant. Conclusion. The diagnosis verification is based on data obtained by microbiological and/or histological, cytological studies. Studies of resection samples from TB suspects significantly improve diagnostic effectiveness.