In this study, it was aimed to determine the levels of vitamin D and some biochemical parameters in calves with pneumonia. A total of 25 calves, 10 clinically healthy as control group and 15 with pneumonia, were used in the study. Biochemical analysis included vitamin D, albumin and total protein levels. When the calves with pneumonia were compared with the control group, it was determined that the levels of vitamin D, albumin (P<0.01) and total protein (P<0.05) decreased statistically significantly. The changes in globulin and albumin/globulin levels were found to be statistically insignificant. As a result, it was determined that vitamin D level decreased in calves with pneumonia. Considering the effect of vitamin D on the immune system, it is thought that vitamin D supplementation may contribute to the recovery of respiratory tract infection and to reducing treatment costs.