Estimation of virulence of T. vaginalis strains injected subcutaneously to mice was done. T. vaginalis strains were obtained from the urinogenital tracts of patients with different clinical forms of trichomonosis. The virulence of T. vaginalis strains measured by infiltration size was found to depend upon a clinical form of trichomonosis. It was moreover shown that the cutaneous infiltration size is proportional to a dose of Trichomonas administered subcutaneously. Histopathological analysis of cutaneous infiltration itself is not decisive as to the strains virulence, yet in addition to macroscopic examination it may be a criterium in the studies on strain pathogenicity
