Moderate sedatives have been increasingly used to improve patient comfort during flexible bronchoscopy (FB). However, routine use of moderate sedation during FB is controversial because its efficacy and safety are not well established. This study aims to evaluate the efficacy and safety of moderate sedation during FB. A search was made of Medline, EMBASE, and the Cochrane Library to May 2014. Randomized controlled trials (RCTs) and quasi-RCTs were included. The main analysis was designed to examine the efficacy of moderate sedation during FB in sedation than no-sedation. The willingness to repeat FB was significantly more in sedation than no-sedation (odds ratio [OR] 2.30; 95% confidence interval [CI] 1.11-4.73; P = 0.02; I2 = 22.5). The duration of FB was shorter in sedation group than no-sedation group (standardized mean difference [SMD] -0.21; 95% CI -0.38 to -0.03; P = 0.02; I2 = 78.3%). Event of hypoxia was not significantly different between sedation and no-sedation groups (OR 0.86; 95% CI 0.42-1.73; P = 0.67; I2 = 0%). The SpO2 during procedure was not different between sedation and no-sedation groups (SMD -0.14; 95% CI -0.37 to 0.08; P = 0.21; I2 = 49.9%). However, in subgroup analysis without supplemental oxygen, the SpO2 was significantly lower in sedation than no-sedation group (SMD -0.45; 95% CI -0.78 to -0.11; P = 0.01; I2 = 0.0%). According to this meta-analysis, moderate sedation in FB would be useful in patients who will require repeated bronchoscopies as well as safe in respiratory depression. To our knowledge, although the various sedative drugs are already used in the real field, this analysis was the first attempt to quantify objective results. We anticipate more definite and studies designed to elucidate standardized outcomes for moderate sedation in FB.