In the past decade the determination of enzyme activity in blood serum, organs and tissues gained an innocuous meaning in the veterinary medicine, especially in the early stages of diagnosis of different metabolism abnormalities. However, the experience gained from the human medicine, without a detail analyses could not be applied on domestic animals and poultry, because of the fact that the enzyme activity in the cells of different animal tissues and organs differs from those of the humans. This explains the different diagnostic meaning of the enzyme activity in animals and humans. Up to date, an extensive research of the enzyme status is done, in order to gain information for their importance in the biochemical processes in the organism, disturbances in the cell membrane transport, disease diagnosis and nutritional disorders.The influence of different stress factors and conditions upon enzyme activity both in serum and tissues is still one of the major topics in many researches. In the first week after hatch important physiological changes occur in chick organism. In the same time, in the first 24-48 hours, they are exposed to the influence of different stressors such as transportation to the hatchery along with feed and water deprivation, what gives the assumption that changes do occur in the serum enzyme activity in the first days after hatch. As literature data on the influence of food and water deprivation upon serum enzyme activity are poor and often very contradictory, this paper will try to contribute to the extensive research on the topic and clear some misunderstandings. For that purpose serum activities of the following enzymes were analysed: alanine aminotransferase, aspartat aminotarnsferase, gamma glutamile transferase, actate dehydrogenase and alkaline phosphatase.