ObjectiveTo explore the process and characteristics of fever induced by dry yeast, 2,4-dinitrophenol, lipopolysaccharide (LPS), and bacterial endotoxin ( standard substance) in SD rats, and to compare the influence of different concentrations of exogenous pyrogens on the fever process.Methods To establish rat fever models induced by dry yeast (2 g/kg, 1 g/kg), and 2,4-dinitrophenol(30 mg/kg, 15 mg/kg), LPS (100 μg/kg, 20 μg/kg), and bacterial endotoxin (120 EU/kg, 60 EU/kg), record the fever values at different time points, draw the average fever curves, and compare their fever characteristics.ResultsIn the febrile rats induced by subcutaneous injection of dry yeast suspension, temperature began to rise after 2-3 h, reached to the peak value after 6-7 h, and lasted for 20 h. In the fibrile rats induced by subcutaneous injection of 2,4-dinitrophenol solution, the temperature began to rise after 20 min, reached to the peak value after 1-1.5 h, and lasted for 3-5 h. In the febrile rats induced by intraperitoneal injection of LPS or bacterial endotoxin ( standard substance), temperature began to rise after 30 min, then the fever curves were biphasic or triphasic, and lasted for 5 h to 8 h.Conclusions Different exogenous pyrogens at different concentrations cause different fever process and characteristics in SD rats. In antipyretic experiments, suitable fever models should be appropriately selected based on the nasture of the tested drug and according to the types of fever process and characteristics of the used animal models. 