Bladder cancer is one of the most common onco-urological diseases, ranked second in frequency among all tumors of the urinary system after prostate cancer. At the time of detection of the primary tumor, approximately 75% of patients have no invasion into the muscularis layer (non-muscle-invasive carcinoma), with tumor growth limited to the basal membrane (stage Ta) or submucosal base (stage T1). Removal of the tumor in a «unified block» (laser en-bloc resection or L-ERBT), unlike routine transurethral resection, allows to obtain qualitative biopsy material for precise pathomorphological staging of the tumor process. In order to accurately stratify a patient into one or another risk group, verification of the following morphological parameters is required: degree of tumor differentiation and its malignancy, depth of invasion, foci of carcinoma in situ at resection margins, presence or absence of lymphovascular invasion. Identification of tumor variant histology is also recommended. Information on presence or absence of detrusor elements in the specimen is necessary in the morphological report, as this parameter is considered as a criterion of radically performed tumor removal. According to ICCR recommendations (International Collaboration on cancer reporting), it is recommended to use subclassification of T1 stage using all possible criteria: volume and/or depth of invasion (assessed in mm), and/or width of invasion «spot» (assessed in mm), and/or involvement of anatomical structure — muscularis mucosae. Full morphological examination of the material obtained during the primary resection of the tumor is an important step in the diagnosis and treatment of bladder cancer, as it allows to stratify the patient into one or another risk group and, accordingly, allows to develop a personalized postoperative management.