Recommendations on the preparation and use of a solid culture medium are given; age changes in the colonies of leptospires belonging to different serovars and serogroups have been studied in their dynamics; the absence of relationship between the form of the colonies, the serovar and serogroup of the cultures, their virulence, as well as the region, time and source of their isolation has been established, which makes it impossible to use these parameters for the differentiation of Leptospira strains belonging to different serovars on solid culture media.