Knowing the blood composition and determining the range of reference values for individual species of domestic animals is a key factor in monitoring their individual and herd health. The aim of the study was to determine the values of selected morphological and biochemical blood parameters, and also to compare the results obtained for farm red deer (Cervus elaphus) with fallow deer (Dama dama). Blood haematological parameters were determined using an automatic haematological analyzer with appropriate software, while biochemical parameters were determined using an automatic analyzer using the spectrophotometric method. The values of morphological and biochemical blood parameters of both deer species were close to the reference values of the blood of domestic ruminants. The only significant differences concerned the level of glucose and total cholesterol. Mean glucose levels of 145.90 ± 28.56 g/dl in red deer and 96.31 ± 14.51 g/dl in fallow deer were higher compared to glucose levels in sheep, goats and cattle. In contrast, the cholesterol level of 59.90 ± 3.18 mg/dl and 77.23 ± 13.74 mg/dl, respectively, in of the researched species was significantly lower compared to the reference level for domestic ruminants. To conclude, it can be assumed that these differences in blood composition may result from the species diversity of the tested animals compared to sheep, goats and cattle. In addition, it should be borne in mind that different husbandry procedures are used for these species, including limited interference with their feeding habits, which in this case are closer to the conditions of their natural habitat