A comparative analysis of the proliferative activity of inflammatory infiltrate cells and the distribution of collagen type I and III in granulomas formed in the area of contact of mesh materials made of polypropylene (PP Std Light) and titanium-coated polypropylene (TiMesh) was performed via polarized microscopy and immunohistochemical detection of Ki-67 protein. Mesh materials were implanted in the soft tissues of the lumbar region of rats. The number of proliferative cells around implants made of the standard polypropylene (PP Std Light) 7 days after the operation was detected with the use of antibodies to Ki-67 protein to be less than the number of those around titanium-coated polypropylene (TiMesh) (29.1 ± 5.7 and 33.6 ± 3.1%, respectively, p < 0.001). The similar differences were revealed 1 month after the beginning of the experiment (15.9 ± 4.3 and 26.9 ± 3.6%, respectively, p < 0.001). Various types of collagen fibers in granulomas around the implanted mesh materials were detected in polarized light with the use of sections stained with Sirius Red. The ratios between collagen fibers type I and III in granulomas around PP Std Light and TiMesh materials determined 7 days after the operation were 1.085 ± 0.022 and above 1.107 ± 0.013, respectively (p = 0.017). The ratio increased to 1.174 ± 0.036 and 1.246 ± 0.102, respectively (p = 0.045) 1 month after the operation. The obtained results suggest that the titanium coating of polypropylene stimulates the formation of collagen type I and more mature connective tissue around mesh endoprostheses. © 2016, Pleiades Publishing, Ltd.