OBJECTIVE: The objective of our study was to retrospectively evaluate the incidence of and the risk factors for pneumothorax and chest tube placement after CT fluoroscopy-guided lung biopsy. MATERIALS AND METHODS: We analyzed 1,098 CT fluoroscopy-guided lung biopsies conducted with 20-gauge coaxial cutting needles for 1,155 lesions in 1,033 patients. Apart from evaluating the incidence of pneumothorax and chest tube placement, the independent risk factors for pneumothorax and chest tube placement for pneumothorax were determined using multivariate logistic regression analysis. RESULTS: The overall incidence of pneumothorax was 42.3% (464/1,098). Chest tube placement was required for 11.9% (55/464) of pneumothoraces (5.0% [55/1,098] of the total number of procedures). The significant independent risk factors for pneumothorax were no prior pulmonary surgery (p = 0.001), lesions in the lower lobe (p < 0.001), greater lesion depth (p < 0.001), and a needle trajectory angle of < 45 degrees (p = 0.014); those for chest tube placement for pneumothorax were pulmonary emphysema (p < 0.001) and greater lesion depth (p < 0.001). CONCLUSION: Pneumothorax frequently occurred and placement of a chest tube was occasionally required for pneumothorax after CT fluoroscopy-guided lung biopsy. To reduce the risk of pneumothorax necessitating chest tube placement, physicians should adopt the shortest needle path to the lesion.