The aim of this study was to evaluate the serum proteins electrophoretic pattern and the concentrations of acute phase proteins in calves with chronic bronchopneumonia. Twenty-eight calves with clinical symptoms of disease were included into the evaluation. Blood serum was analyzed for total protein concentrations (TP), total and relative values of serum protein fractions, albumin/globulin ratio (A/G) and the concentrations of selected acute phase proteins -haptoglobin (Hp), serum amyloid A (SAA), and fibrinogen (Fbg). The results recorded in sick animals were compared with those in 36 clinically healthy calves as control group. In calves suffering from chronic bronchopneumonia we found significantly higher total serum protein concentrations than in healthy calves (p<0.001). In sick calves a marked shift in the concentrations of most of the protein fractions was observed, with significantly higher mean total values of α 1 -(p<0.001), β 1 -(p<0.01), β 2 -(p<0.001), and γ-globulins (p<0.001) and relative mean values of α 1 -(p<0.01), β 2 -(p<0.01), and γ-globulins (p<0.001). On the other hand, the concentrations of albumin and A/G ratios were in calves with respiratory diseases significantly lower than those measured in healthy ones (p<0.001). The mean concentrations of α 2 -globulins did not differ significantly between the two groups of animals. In the affected calves significantly higher mean values of Hp, SAA, as well as Fbg (p<0.001) were described. The presented results suggest a marked effect of chronic bronchopneumonia in calves on most of the evaluated protein profiles and acute phase protein variables with a marked shift in the albumin and globulin concentrations.