Introduction. The clinical efficiency of oral mucosa grafts used for augmentation urethroplasty has been proven. However, a small number of studies in literature are dedicated to the determination of pathologic changes in grafts during the engraftment in the urethra.
Aim: to assess the histopathologic evolution of oral mucosa graft used for augmentation urethroplasty.
Material and methods. A total of 15 patients aged 19–67 years with penile and combined penile/bulbar urethral strictures of length 3.5–11 cm were undergone to two-staged urethroplasty by Asopa technique. In 9 cases the pathologic study of oral mucosa grafts after sampling (buccal mucosa in 5 cases and lip mucosa in 4 cases) and 6 months after their engraftment in the urethra during the second stage of urethroplasty was performed. In other 6 cases the graft tissue in patients with recurrent stricture that occurred 12–24 months after tubularization and requiring additional intervention was studied.
Results. The general structure of mucosal graft was preserved 6 months after sampling. The dystrophic changes in epithelium, inflammatory infiltration and foci of fibrosis in subepithelial layer were observed. Buccal grafts were distinguished by a smaller epithelium thickness and the presence of keratinization foci. The grafts also retained their structure after 12–24 months. A decrease in the severity of chronic inflammatory reaction and the absence of keratinization of the squamous buccal epithelium were found. The stricture in the area of anastomosis was characterized by the presence of sclerotic and fibrous connective tissue covered with urothelium.
Conclusion. The oral mucosa grafts completely preserve their histologic structure during 1–2 years and they are not involved in recurrence of urethral stricture, which develops in the area of anastomosis between graft and native urethra.

Keywords: urethral stricture, augmentation urethroplasty, graft, oral mucosa, morphological study