The aim of the present study was to determine concentrations of haptoglobin, ceruloplasmin and some biochemical parameter levels and to investigate their diagnostic importance in calves with diarrhea. For this purpose 25 calves with diarrhea were used as working group and 10 healthy cattle as control group. Blood samples were collected from Jugular vein in tubes without anticoagulant. Blood samples were centrifuged and the resulting serum samples were stored at -20 °C until laboratory testing. Samples were used to determine the concentrations of haptoglobin, ceruloplasmin, aspartate transaminase (AST), gamma-glutamyl transferase (GGT), urea, creatinin, total protein and albumin. Results of present study indicated that the concentrations of AST, GGT, urea, creatinin, total protein, haptoglobin and ceruloplasmin were significantly increased in calves with diarrhea. In conclusion; in this study in calves with diarrhea occurs acute phase response and as a result haptoglobin and ceruloplasmin synthesis increased and it was determined that significant changes occurred in the biochemical parameters.