SummarySerum concentrations of acute phase proteins can provide valuable diagnostic information in the detection and monitoring of disease. The available information on the acute phase response in cats with anaemia is limited. The aim of this study was to retrospectively evaluate serum concentrations of haptoglobin, serum amyloid A, α1 acid glycoprotein and their clinical importance in cats with anaemia. Thirty-four anaemic cats and ten healthy cats were enrolled this study. After individual diagnoses had been established, the cats were divided into three groups (healthy group, haemolytic group and non-haemolytic group). Serum acute phase protein concentrations were analysed using specific commercially available test kits in an ELISA reader device. Serum amyloid A and serum α1 acid glycoprotein concentrations were significantly higher in the anaemic groups compared with the healthy group. Haptoglobin concentrations were significantly higher in cats from the non-haemolytic anaemia group than they were in healthy animals and those from the haemolytic anaemia group. Although serum haptoglobin concentrations were lower than in the healthy group, there was no significant difference between the haemolytic anaemia group and the healthy group. The results of this study suggest that serum amyloid A and α1 acid glycoprotein could be useful in the diagnosis and determination of inflammation in cats with anaemia. Serum haptoglobin depletion may be used for diagnosis of haemolysis in cats with haemolytic anaemia. In addition, this study has contributed to the limited data available on acute phase protein concentrations in cats with anaemia.