A.M. Elovikov, Perm State Medical Academy. Surgical treatment of frontal sinus diseases is a pressing issue in otolaryngology. According to the literature, postoperative recurrence of inflammatory processes in the frontal sinuses (FS) develops in 5-60% of cases. To prevent recurrence of frontal sinusitis, various techniques have been proposed for plastic surgery of trepanation defects, frontonasal junction, or occlusive surgery of the FS using various grafts and implants. Since 1998, the Otolaryngology Clinic of Perm State Medical Academy has been using reconstructive surgeries using the carbon material "Uglekon-M" to treat inflammatory FS diseases. This material was developed by specialists from the Ural Research Institute of Composite Materials in close creative collaboration with researchers from the Perm Medical Academy, and clinical trials were conducted in the clinics of traumatology and orthopedics, military field surgery, surgical and orthopedic dentistry. In terms of chemical composition, the new material is practically pure carbon (carbon content 98.5-99.9%), possessing biological inertness, thermal stability, and high mechanical strength. Its elastic modulus and internal architecture are identical to those of native bone. "Uglekon-M" grows into bone tissue upon implantation. Objectives and tasks: To determine the incidence and causes of postoperative recurrence of left lateral pelvic diseases. To determine the indications for plastic surgery of bone defects and cavities using "Uglekon-M" structures during left lateral pelvic surgeries. To study the immediate and long-term results of left lateral pelvic surgeries using "Uglekon-M" structures. According to an analysis of archival data from the Perm Otolaryngology Clinic, postoperative recurrence of left lateral pelvic inflammation after conventional surgeries developed in 35±6.1%. The most dangerous in terms of the development of recurrent inflammation are Belogolovov, Jansen-Ritter and Riedel type operations, after which relapses are observed in 80%, 66.7% and 53.8%, respectively. The main cause of the recurrence of the inflammatory process in the left atrium was obstruction of the frontonasal junction due to the cicatricial process, retraction of soft tissues and the development of the osteomyelitic process. We observed 36 patients (19 men and 17 women) aged from 18 to 71 years, who underwent extranasal surgical interventions on the left atrium using "Uglekon-M". Twenty-four patients in this group had complicated frontal sinusitis, 10 patients were admitted with a recurrence of purulent inflammation in the left atrium after previous classical operations. The duration of observation of patients after reconstructive interventions ranged from 1 to 8 years. During surgical interventions, we attempt to preserve the left atrium as an organ. The method of choice is the creation of a frontonasal junction with plastic surgery of the trepanation defect of the left atrium walls using a Uglekon-M plate. For plastic reconstruction of the left atrium walls, we used a plate version of the carbon material. The implant plate, 1 to 3 mm thick, was fixed to the edges of the trepanation defect using bone sutures. The wound was sutured layer by layer with a cosmetic suture on the skin. In cases of recurrent purulent processes in the left atrium after previous surgeries, or in cases of significant sinus wall defects, i.e., in cases where the left atrium loses its ability to regenerate as an organ, we obliterate the bone cavity of the left atrium using the cellular carbon material Uglekon-MYa. We performed plastic surgery of bone defects and cavities with carbon material in a single stage after the debridement stage of the surgery for uncomplicated frontal sinusitis. In complicated cases, the second stage after the inflammatory processes in the surrounding tissues had been controlled was the open wound management in these patients. Our reconstructive surgery technique using Uglekon-M carbon fiber material resulted in good functional and aesthetic results in all patients. No recurrences of pathological processes in the left atrium were observed. Conclusions: The main causes of postoperative recurrence of inflammation in the left atrium are obstruction of the frontonasal junction due to scar and granulation tissue, retraction of soft tissues of the frontal region into the sinus lumen, and the development of osteomyelitic processes. Reconstructive surgeries using Uglekon-M carbon fiber material are optimal for preventing recurrence of pathological processes in the frontal sinuses.