PURPOSE:To evaluate the duration of room air tamponade and its associated factors. STUDY DESIGN:Retrospective cohort study METHODS: The present study reviewed the medical records of patients who received room air tamponade after vitrectomy between Jun 2015 and Dec 2016. The room air duration was assessed by patient interviews 2 weeks after surgery. Relationships between the variables and tamponade duration were determined using logistic regression analysis. The remaining air level was determined from medical records. RESULTS:The room air tamponade had dissipated by 11.1 ± 1.3 days after surgery. The duration was 11.2 ± 1.3 days for eyes with a spared posterior capsule, longer than the duration in other eyes (10.1 ± 0.9 days). Increased axial length was correlated with increased duration. Axial length and a spared posterior capsule were significantly correlated with tamponade duration. Its half-life was presumed about 3.3 days. The room air seems to be absorbed at a constant rate. CONCLUSION:The data suggest that room air tamponade remains in the vitreous cavity for an average of 11.1 days. Axial length and posterior capsule status were associated with duration.