Evidence from observational studies and clinical trials has reported that gut microbiota (GM) was associated with chronic lung diseases (CLDs). However, the causal relationships between GM and CLDs have yet to be fully ascertained. The Mendelian randomization (MR) based causal analysis was performed using the genome-wide association study (GWAS) summary statistics from the MiBioGen and FinnGen consortium. GM served as exposure, and CLDs were taken for outcomes. Inverse variance weighted, MR-Egger, and weighted median methods were utilized to examine the causal association between GM and CLDs. ...