ObjectiveTo investigate the changes of serum procalcitonin (PCT) levels and the correlations between PCT and GOLD (Global Initiative for Chronic Obstructive Lung Disease) recommended antibiotic principles in elderly patients with acute exacerbations (AE) of group D chronic obstructive pulmonary disease (COPD).Methods102 elderly inpatients with group D AECOPD and 40 healthy donors were recruited.Antibiotics were given to the AECOPD patients under the GOLD recommended antibiotic principles and serum PCT levels were measured before and after treatment.Results(1)The serum levels of PCT in elderly patients with untreated AECOPD ［0.07(0.05,0.68) ng/mL］ was significantly higher than those in posttreatment group［0.05(0.38,0.10)ng/mL］ or healthy control group［0.05(0.01,0.06) ng/mL］(P<0.05 both).The patients who met the GOLD recommended antibiotic principles had lower posttreatment PCT levels［0.05(0.00,0.07) ng/mL］than those who did not meet the principles ［0.06(0.05,0.25) ng/mL］（P<0.05）.(2)There were no significant correlation between PCT levels and whether the GOLD recommended antibiotic principles were met by logistic regression analysis(P>0.05).ConclusionsIncreased serum PCT level in elderly patients with group D AECOPD is expected to become a new indicator for guiding antibacterial treatment, independent of GOLD recommended antibiotic principles.