Objective: This study aimed to determine the predictive value of the neutrophil to lymphocyte ratio (NLR) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).\u00a0\u00a0\u00a0 Methods: A retrospective study was conducted from March 2012 to May 2016 in Fuxing Hospital, Capital University of Medical Science. We collected 906 cases (525 males, 381 females, mean age 81.86\u00b19.75 years) diagnosed with AECOPD. The NLR was calculated from their white blood cell (WBC), neutrophil (NEU), and lymphocyte (LYM)counts, which were obtained at laboratory examination.\u00a0\u00a0\u00a0 Result: After treatment, 698 patients with AECOPD improved. The NLR was higher at admission (6.89\u00b16.82) than after treatment (4.19\u00b15.11) (P=0.000). The area under the receiver operating characteristic curve (AUC) of the NLR for predicting the 28-day mortality rate was 0.737. Using 8.130 as the critical NLR value, the sensitivity was 60.5%, and the specificity was 74.8%. The AUC of the NLR for predicting the frequency of the need for invasive mechanical ventilation was 0.732. Using 10.345 as the critical NLR value, the sensitivity was 54.3%, and the specificity was 84.8%. The AUC of WBC, NEU and LYMfor predicting 28-day mortality and the need for invasive mechanical ventilation in these patients were all less than 0.7. An increased NLR was an independent risk factor for 28-day mortality (OR=1.067, P=0.000), intensive care unit occupancy (OR=1.046, P=0.000), and the need for invasive mechanical ventilation (OR=1.042, P=0.000). Compared with those patients without comorbidities, patients with renal dysfunction or upper gastrointestinal bleeding had an increased risk of death within 28 days (OR=3.102, OR=4.598, respectively), ICU admission (OR=2.228, OR=3.103, respectively), and the need for invasive mechanical ventilation (OR=3.572, OR=4.279, respectively).\u00a0\u00a0\u00a0 Conclusion: In patients with AECOPD, the accuracy of the NLR for predicting the 28-day mortality rate and frequency of the need for mechanical ventilation was significantly higher than the accuracy of WBC, NEU and LYMcounts. AECOPD patients with an NLR\u22658.130 had higher 28-day mortality rate, while those with an NLR \u226510.345 were more likely to need invasive mechanical ventilation.