Individual elements of the coloration pattern of Hirudo medicinalis are described and analyzed. Longitudinal stripes on the dorsum and the distribution of dark pigment on the venter are used as the basis for the investigation. A frequency distribution of different variations of the pattern in natural populations is revealed. Frequencies of certain variations of the coloration are more similar in geographically approximate populations in comparison with distant populations. Therefore, such elements can be useful for phylogeographic analysis. There is a weak statistical association between some elements of the dorsal coloration. No reliable dependences between variants of the dorsal and ventral patterns are found. By and large the high variability of the coloration pattern of H. medicinalis is recorded. The variability is a result both of numerous variations of each element and nearly free combinations of the elements.