The purpse of this study is to determine the effects of boron (B) utilisation on hematological parameters in order to protect from gentamicin side effects. Totally 56 Wistar Albinomale rats were randomly divided into eight groups containing 7 animal per group. While first group served as a control(fed a diet without boron), experimental groups were as follows; gentamicin group (100 mg/kg, i.p.), B-5 group (5 mg/kg B, i.p.), B-10 group (10 mg/kg B, i.p.), B-20 group (20 mg/kg B, i.p.), B-5 + gentamicin group (5 mg/kg B and 100 mg/kg gentamicin, i.p.), B-10 + gentamicin group (10 mg/kg B and 100 mg/kg gentamicin, i.p.), and B-20 + gentamicin group (20 mg/kg B and 100 mg/kg gentamicin, i.p.). In experimental period lasted totally 14 days, B application started to be given 4 days before injection of gentamicinto rats and was completed the fourteenth dayof the experiment. Gentamicin started to be given to rats on the fourth day and finished on the twelfth dayof the experiment. In the end of the experiment, the blood samples were taken from the animals by cardiac punctureunder anaesthesia. In the blood smaples, erythrocyte, leukocyte and platelet counts, haematocrite value, hemoglobin concentration, mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobine concentration (MCHC) were determined. Gentamicin decreased leucocyte counts and haematocrite value. High boron utilization (20 mg/kg B, i.p.) decreased significantly leucocyte counts. In conclusion, the boron supplementation has no a preventive effect on leucocyte counts reduced by gentamicin.