The subject of the research was the effect of two types of the horse beans, AKORD and LEO, concentrating different tannin on selected hematological and biochemical parameters of rat’s blood. The object of the research was 40 rats of the Bufflo strain. There were 5 groups of 8 rats each. The first group was the control group. Every group was fed on different species of horse beans, with different doses except for the first group. The control group was fed on a fodder wihout horse bean. No changes in haematologicall parameters were observed. It was noticed that the level of cholesterol in the blood serum increased except in the group where 60g horse bean AKORD was added. The level of triglycerides was reduced in every group. The greatest reduction was in the second group where 30g horse bean AKORD caused a decrease of the HDL fraction and an increase of the LDL fraction. Along with the increase of tannin content, a higher level of glucose was observed. Horse bean LEO caused a significant increase of protein content. The impact of horse bean LEO on liver enzymes was also observed. The level of AlAT decreased and AspAT increased.