Objective To explore the role of procalcitonin(PCT)in antibiotics therapy of elder patients with community acquired pneumonia(CAP). Methods Sixty-two elderly patients with CAP who hospitalized in Linxi Hospital of Kailuan General Hospital from Jan. 2010 to Dec. 2013 were selected as study subjects,and their age span were 54. 0 - 87. 0 years old. All the patients were randomly divided into conventional therapy group(n= 33)and PCT group(n = 29). The use of nntibiotics in conventional treatment group was based on clinical symptoms of patients and the standard of antibiotics application in clinic,while in PCT group was based on PCT serum levels. The main observation indexes including days of antibiotics use,cost of antibiotics use,hospital stay, total cost of hospital stay,clinical efficacy,aggravating cases and death cases. Results The days of antibiotics use,cost of antibiotics use,hospital stay,total cost of hospital stay in PCT group were((12. 2 ± 1. 4)d, (3 341. 9 ± 52. 73)yuan,(12. 1 ± 1. 8)d,(5 346. 2 ± 1 274. 5)yuan)lower than that in conventional therapy group((16. 9 ± 3. 5)d,(3 816. 28 ± 84. 27)yuan,(14. 7 ± 2. 9)d,(6 653. 2 ± 1 132. 8)yuan),and the differences were significant(t = 6. 77,26. 14,4. 17,4. 28;P < 0. 001). There were no significant difference in terms of clinical prognosis( clinical efficacy,aggravating cases and death cases)( P > 0. 05). Conclusion Procalcitonin can guide antibiotics application in the elderly patients,and then prevent the abuse of antibiotics.