The description of pathomorphological and pathogistological changes in parenchymatous bod-ies, tubular bones and red marrow of the cats which have died from gemobartonellosis is presented in the study. The objects of the study were 10 cats which had died from gemobartonellosis. For histo-logical study from each animal the slices of lung, heart, spleen, liver, kidney, ulna and radius were selected, which were sawed into slices having the thickness of 1 cm3. The material was fixed in 10 % neutral formalin for 3-5 days and washed during 24 hours in running water, carried out through ethyl alcohol of increasing concentration (60, 70, 80, 96, 100), embedded in paraffin. Then by the standard technique the sections of 5-8 microns thick by means of MPS-P microtome were made. Histologi-cal preparations were photographed by means of the complex of visualization of images on the basis of Olympus 2000. The sections were painted with hematoxylin and eosin. The decalcification of bones was carried out in 5 % solution of trichloroacetic acid for 5 days with daily change of solution. Then the material was taken through alco-hols of increasing concentration and xylene and filled in histological Gistomix environment ("BioVitrum", Russia) with use of histological pro-cessor of Tissue-Tek VIP™ 5Jr type and station of paraffin filling of Tissue-Tek® TEC™ 5 of Sakura firm (Japan). Histological sections were made 5- 7 microns thick and painted with hematoxylin and eosin (Bio-Optica (Italy) and "BioVitrum" (Russia)) on automatic multistainer of Prisma™ of received blocks. The microscopy of sections was carried out on digital microscope of Olympus BX 45. From each histological preparation 10 digital pictures (in a format of jpg, 3136 × 2352 pixels in size in a pal-ette of 24 bits) were taken in incidentally chosen fields of vision at the increase ×100, ×200, ×400 and ×1000. In gemobartonellosis of cats the follow-ing pathoanatomical changes were noted: acute parenchymatous myocarditis, congestive pulmo-nary edema and focal alveolar emphysema, hemor-rhagic glomerulonephritis, hyperplasia of the spleen, toxic degeneration of the liver.