Abstract: Objective To investigate the role of serum interleukin-6 (IL-6), C-reactive protein (CRP) and procalcitonin (PCT) in the early diagnosis of hemolytic streptococcal infection. Methods Clinical data about patients who had streptococcal infection in October 2010, including serum concentrations of IL-6, white blood cell counts, neutrophil percentage, CRP and PCT were determined and compared after clinical treatment, in order to analyze the causes of changing in inflammatory factors. Results The number of leukocyte, neutrophil percentage and the level of IL-6 increased significantly during clinical treatment, and they all decreased after 2 d clinical treatment (11.6±3.2)×10⁹ vs (6.5±1.9)×10⁹, (79%±10% vs 61%±8%), 25.1(16.9, 39.2) ng/L vs 1.5(1.5, 1.5) ng/L, the difference was of statistically significant (P=0.000). The level of CRP 0.7(0.3, 1.6) mg/L vs 2.7(0.9, 4.7) mg/L increased significantly after medical treatment, and the positive rate of PCT had no significant differences between before and after treatment. Conclusion The reaction of IL-6 is rapid in the early time of bacterial infection, and it has a consistent trend with WBC and N%. The increase of CRP level is lagging behind, and PCT shows no significant increase in acute focal bacterial infection. IL-6, WBC and N% are the diagnostic clues in the early diagnosis of hemolytic streptococcal infection.