Abstract： Objective To evaluate the value of serum procalcitonin (PCT) in antibiotics used for the treatment of acute exacerbation of asthma. Method From February 2007 to July 2009, a total of 158 patients with asthma were randomly (random number) assigned to PCT group ( n = 77) or to control group ( n = 81 ). The PCT levels of all patients were measured. On the bases of routine treatment, the employment of antibiotics in control group was determined by the guidebook, and patients in the PCT group were treated with antibiotics guided by the levels of serum PCT. The antibiotics treatment was employed as PCT level ＞0.25 ng/mL, and was not employed as PCT level ＜ 0.25 ng/mL. The rates of antibioties employment were observed. Results The rate of antibiotics employment in PCT group (45.4%) was lower than that of the control group (77.8%) (x2 = 17.15,P =0.000). Conclusions PCT could be used safely as guidance of antibiotics employment for the treatment of patients with acute exacerbation of asthma, leading to appropriate use of antibiotcs.