One of the triggers of infectious processes developing in the kidney after contact laser lithotripsy is calculus disintegration followed by the release of bacteria and toxins from the biofilm. Prevention urgency determines the search for new mechanisms and methods of laser calculus fragmentation without scattering of fragments and microbial dissemination into the pelvicalyceal system of the kidney. The aim of the study was to evaluate the possibilities of applying the technology of urinary calculus fragmentation with continuouswave diode lasers of different wavelengths using fiber light guides with strongly heated distal tips for controlled fragmentation and minimization of traumatic effects on the adjacent tissues. Materials and Methods. To fragment postoperative samples of porous urinary stones (n=58), we applied standard certified continuouswave diode 10 W lasers with fiber output to quartz light guides, their distal tips being coated with a layer of graphite microparticles in silicone varnish. The quality of stone fragmentation using lasers with wavelengths of 0.81 (n=17), 0.97 (n=22), and 1.47 µm (n=19) and identical quartz light guides were evaluated. Control of laser-induced heating of the urinary tract tissues adjacent to the stone was carried out on the model medium with a thermocouple. Simulation of intraoperative errors (short contact with the ureteral wall as the result of the fiber slipping off the stone surface) was performed on the ureteral wall took post mortem. Tissue condition was assessed using histological sections stained with hematoxylin and eosin. Results. The average fragmentation time depended on calculus density and cross-sectional dimension and was 12-15 s. All selected stones, including those potentially infected, with X-ray density 119 to 1735 HU were fragmented effectively both in liquid and air. Assessment of temperature regimes provided by lasers with 0.81 and 0.97 µm wavelengths showed that the stone surface temperature during fragmentation in the air reached 40 and 57°C, respectively, and it was 25 and 33°C in liquid. The obtained morphological and thermometric data suggest safety of lasers used for controlled fragmentation of potentially infected urinary calculi. Conclusion. The use of continuous-wave diode lasers with strongly heated distal fiber tips at 0.81 and 0.97 µm wavelengths makes it possible to successfully fragment potentially infected urinary stones into size-controlled fragments, which may become a significant factor in prevention of systemic inflammatory response in the postoperative period.