The aim of the study was to estimate the effect of tylosin and prebiotics (β-glucans and mannanooligosaccharides) added to feed on the selected humoral immune parameters in calves. Among them, the concentrations of total protein and γ-globulin, titre of conglutinin, and activity of alkaline phosphatase were tested in calf serum. The study was performed on 36 clinically healthy, Black and White Lowland breed calves, aged 6-8 weeks. The animals were randomly divided into three equal groups. The calves in group I were fed with feedingstuff supplemented by the tylosin. The second group of calves received prebiotics and the control (group III) was fed the same feedingstuff without the additives. The results indicated that supplementation of feedingstuff with prebiotics and tylosin had a positive effect on the total protein and gammaglobulin concentrations. The titre of conglutynin was significantly higher in the group of calves fed prebiotics in comparison with the control group. The activity of alkaline phosphatase was higher in both experimental groups of animals but a stronger activity of this enzyme was observed in the calves fed tylosin.