The objective of present study was to assess the diagnostic value of the concentration of haptoglobin, one of a series of acute phase proteins that is found in the blood of both humans and animals. A total of 79 random horse sera(10 dam and 69 foals) with clinically normal were analyzed by ELISA. The mean serum concentrations of haptoglobin of dam and foals were 1.67${pm}$0.52mg/ml(range 1.08∼2.12 mg/ml), 1.65${pm}$0.50 mg/ml(range 0.50∼2.66 mg/ml), respectively. These results may provide basic information for developing a useful marker system to monitor infections early in horses.