It is known that boron has various biological functions in plants and animals, and can have positive effects when used in appropriate doses, but can have toxic effects in high doses. In this study, it was aimed to examine the effects of different doses of boron addition to quail feed on macroscopic, microscopic and antioxidant and oxidant levels on lymphoid organs. A total of 100 Japanese Quails were used in the study, and the groups were; Group I; Control (Boric acid (BA): 0 mg/Kg), Group II; feed 100 mg/Kg BA, Group III; feed 300 mg/Kg BA, Group IV; feed 500 mg/Kg BA. Starting from the first week, 5 quails were randomly selected from each group and a total of 20 quails were euthanized. Blood samples were taken and glutathione, glutathione peroxidase, superoxide dismutase, catalase, and malondialdehyde levels were measured by spectrophotometric method. After euthanasia, lymphoid organs were taken, weighed, and placed in a 10% formalin solution. In blood analysis, it was seen that among the groups, only the glutathione peroxidase level increased significantly in the Feed 300 group (p<0.001). In lymphoid organ weight measurements; spleen, thymus and Bursa Fabricius increased in the control and boron supplement groups in the first 4 weeks, showed no change (spleen) or decreased (thymus and bursa) in the 5th week, and the increase in the first 4 weeks was similar in all groups and was statistically significant. It was found to be not significant (p>0.05). In the histopathological examination, no pathology was found in the lymphoid organs of the control and boron supplement groups. Although mild lymphoid depletions were observed in some animals in all groups, it was not statistically significant (p>0.05). As a result, it was concluded that boron supplementation could contribute to antioxidant activity by increasing glutathione peroxidase levels in quails, and did not cause lymphoid organ pathology at the given doses, but did not show any effect on these organ weights. These findings indicate that the effects of boron on the lymphoid system need to be further investigated.