The aim of the study was to estimate the prevalence of splenic diseases in dogs. 97 samples of spleen tissues and spleen tumors were obtained during laparotomy in veterinary clinics and send for histopathological evaluation. The medical records were reviewed for sex, breed and age of animals and type of steated splenomegaly (diffuse or nodular). The tissue samples for histopathology were fixed in 10% buffered formalin, embedded in paraffin, sectioned at 5-6 µm, and stained with hematoxylin-eosin method or others if needed. Primary and metastatic tumors of the spleen were the most commonly determined pathology (57% splenic lesions), nonneoplastic ones were more seldom observed. The most common type of splenic tumors was haemangiosarcoma (40% of splenic neoplasms), then spindle cellular sarcomas (24%), lymphomas (16%), more seldom were haemangiomas and metastatic tumors. Hemangiosarcomas were observed most commonly in male German shepherd dogs, 10 years of age. The majority of nonneoplastic lesions determined diffuse or local circulatory disturbances and hematomas, hyperplastic changes were rarely observed. The association between type of splenomegaly and kind of splenic lesions was not determined, but the nodular splenomegaly was more frequently observed in cases of hematomas and neoplasms of endothelial origin.