Introduction. Ureteral stents are widely used in urological practice. However, stent placement carries a high risk of complications, the most serious of which are incrustation and infectious biofilms formation on the stent surfaces. These complications limit the optimal period of stent functioning, reducing the time for adequate drainage function maintaining.

Aim. The purpose of the 1st part of the review is to study the mechanisms of incrustation and biofilms formation on the surface of internal drains. Knowing these mechanisms is essential for the subsequent selection of materials and coatings for ureteral stents.

Materials and methods. The literature search was performed in the Pubmed, Web of Sience, Science Direct, Scopus, Cyberleninka, elibrary, TsNMB and other databases for the period from 1984 to 2020 for the following keywords: ureteral stent, incrustation, biofilm, urolithiasis, bacteriuria. More than 100 publications were found, 84 papers that most fully correspond to the article topic were analyzed. 36 papers formed the basis of the first part of the review.

Results. In recent years, progress in the development of new materials and coatings for stents has been made. New engineering solutions to increase the biocompatibility of drainages reducing their susceptibility to the salt and bacterial deposits formation are being sought. New stent features can help eliminate or reduce the incidence of some common complications.

Conclusion. The search for new bioinert materials for the stent manufacture is a promising scientific direction. However, despite the great success in this area, the problem is far from a final solution.