The objective: is to evaluate the effectiveness of the treatment of muscle-invasive bladder cancer (MIBC) by creating an artificial reservoir for the derivation of urine from segments of the small intestine of patients and to study urination and other functions of the urinary system in the postoperative period. Material and methods. During 2019-2020, the SI «Academician O.F. Vozianov Institute of Urology National Academy of Sciences of Ukraine» conducted examinations and treatments on nine patients diagnosed with MIBC at clinical stages T2aN0M0–T3bN0M0. All patients underwent laparoscopic cystectomy and lymphadenectomy, while a third of them underwent open bladder resection at other medical facilities. Among these, three patients received intracorporeal ileoneocystoplasty, whereas in six patients, the procedure involved a change in access from a median laparotomy. The implemented method of orthotopic ileoneocystoplasty during radical cystectomy involves creating an orthotopic artificial bladder from a previously resected segment of the ileum and anastomosing it with the proximal part of the urethra and the distal segments of the ureters. Notably, this method introduces several innovations: firstly, it allows for instrumental intestinal suturing in cases of endoscopic variants of radical cystoprostatectomy, and reduces the necessary length of the ileo-intestinal fragment to 50 cm. Secondly, it involves complete detubularization of the intestine fragment, asymmetrically during its middle 5 cm to form a cervical flap, and symmetrically along the contramesenteric edge for the remaining length. Thirdly, the medial edges of the right and left intestinal segments are initially fixed to the upper edge of the middle segment. Fourthly, after creating the eye of the neck of the future reservoir, the upper and middle thirds of the lateral edge of the right and left intestinal segments are fastened together. Fifthly, the original neck of the intestinal bladder is formed by performing vertical incisions of the pre-created eye of the neck of the reservoir at 12 and 6 o’clock to expand its diameter to 1.0–1.5 cm, followed by eversion and tubularization of the formed semicircles on the urethral catheters using 3–5 nodal sutures and a neck duplication maneuver with two nodal, superimposed parallel to the axis of the neck, sero-muscular sutures with a step between injection and needle puncture of 0.3–0.5 cm. Sixth, after forming the vesico-urethral anastomosis, the free edge of the cervical flap and the lower thirds of the lateral edge of the right and left intestinal segments are sutured, the adoral nd aboral intestinal openings are sealed, a cystostomy drainage is installed through the latter, and a reversible peritonization maneuver is performed. Results. According to the type of intervention, patients were divided into 2 groups: 1 group of open ileoneocystoplasty – 6 patients, 2 group of intracorporeal ileoneocystoplasty – 3 patients. According to the results of the operation, the average volume of the artificial reservoir immediately after the operation was: in group 1 – 180 ml ± 23 ml, in group 2 160 ml ± 50 ml. After 6 months, this volume increased and was 420 ± 68 ml in group 1, 380 ± 50 ml in group 2, which allowed patients to urinate 6-8 times a day and 2-3 times a night in some cases. The postoperative bed-day in group 2 was shorter on average by 7 days (7.2 ± 1.5 vs. 14.2 ± 4.2). In this study, there were no registered cases of leakage of the vesico-urethral anastomosis or its stenosis. Conclusions. Application of the proposed method of orthotopic ilioneocystoplasty during radical cystectomy will allow: – to reduce the total time of the operation in connection with the use of modern methods of intestinal suture provided for in its framework; – to compensate for the possible tension of the vesico-urethral anastomosis, which will lead to a decrease in the frequency and intensity of such postoperative complications and negative consequences as: leakage of the vesico-urethral anastomosis or its stenosis, as well as urinary incontinence at night; – thanks to the original maneuver of forming the neck of the ileal reservoir, reduce the hypermobility of the reconstructed bladder-urethral segment; – reduce the likelihood of metabolic disorders in the postoperative period due to the reduction of the length of the ileal segment removed from the patient; – to unify the technology of orthotopic ilioneocystoplasty within the framework of various approaches to performing radical cystectomy, among them: traditional «open», laparoscopic or robot-assisted.