The study presents comparative data of different age groups of dogs with chronic hepatitis. The aim of the study was to compare the results of clinical and biochemical blood indices in different age groups of dogs with chronic hepatitis. For the study 3 experimental groups were formed: the 1-st group consisted of dogs with chronic hepatitis at the age of 3-6 years (n = 4), in the 2-nd group they were 6-10 years old (n = 5) and in the 3-rd group they were 10-13 years old (n = 6). The results of the studies were processed on the basis of general clinical (GCB) and biochemical blood (BCB) tests. When carrying out BCB the increase of alanine ami-notransferase (ALT) in dogs in all groups was re-vealed. During serum chemistry the increase in alanine aminotransferase (ALT) in dogs in all groups was found. This index was 472.8 ± 2.16 units / l in the 1-st group, 661.17 ± 1.74 units / l in the 2-nd and 659.5 ± 2.96 units / l in 3-rd group, unlike the norm of 10-58 units / l. During GCB anemia was detected in each group of dogs: there were reduced number of erythrocytes; hemoglobin and hematocrit were also below the reference val-ues. Morphological changes in erythrocytes were characterized by poikilocytosis. So, in all groups the number of normocytes and microcytes was in-creased. As a result of conducted studies the in-crease was found in many enzymes: ALT, aspar-tate aminotransferase, alkaline phosphatase, gamma glutaminetransferase, and the decrease in albumin, urea and glucose. During clinical analysis the pattern of anemia, characteristic for chronic diseases,the emergence in blood of poikilocytes in the form of microcytes, macrocytes, acanthocytes was revealed. When comparing the age groups of dogs it was found out that the blood pattern charac-teristic of this disease was identical for dogs of any age.