Background: Bronchiolitis obliterans syndrome (BOS) is a devastating complication that occurs after transplantation. Although azithromycin is currently used for the treatment of BOS, the evidence is sparse and controversial. The aim of this meta-analysis is to evaluate the effects of azithromycin on forced expiratory volume in 1 second (FEV1) and patient's survival. Methods: PubMed, Embase, Cochrane library, Web of Science databases, and the ClinicalTrials.gov registry were systematically searched from inception until December 2020 for relevant original research articles. Random-effects models were used to calculate pooled-effect estimates. Results: Searches identified 15 eligible studies involving 694 participants. For FEV1 (L), there was a significant increase after short-term (<= 12 weeks; P = .00) and mid-term (12-24 weeks; P = .01) administration of azithromycin. For FEV, (%) compared to baseline, there was a significant increase after short-term (<= 12 weeks) administration of azithromycin (P = .02), while there were no statistically significant differences in the medium and long term. When pooled FEV1 % was predicted, it exhibited a similar trend to FEV1 (%) compared to baseline. In addition, we discovered that azithromycin reduced the risk of death (hazard ratio = 0.26; 95% confidence interval = 0.17 to 0.40; P = .00) in patients with BOS post-lung transplantation. Conclusions: Azithromycin therapy is both effective and safe for lung function improvement in patients with posttransplant BOS after the short- and medium-term administration. Additionally, it has been demonstrated a significant survival benefit among patients with BOS post-lung transplant. Higher quality randomized controlled trials and more extensive prospective cohort studies are needed to confirm the effect of azithromycin on patients with posttransplant BOS.