OBJECTIVES:To evaluate the incidence and clinical significance of pneumothorax (PTX) and pulmonary hemorrhage (PH) after CT-guided lung biopsy (CT-LB). To test correlations of PTX and chest tube insertion (CTI) with PH and other imaging and procedural parameters. METHODS:Pre-procedural CT and CT-LB scans of 904 patients were examined. Incidence of PTX and PH and PH location (type-1 along needle track; type-2 perilesional) and severity according to its thickness (low grade < 6 mm; high grade > 6 mm) were recorded. PTX was considered clinically significant if treated with CTI, PH if treated with endoscopic/endovascular procedure. Binary logistic regression analyses were used to determine the effects of different imaging and procedural parameters on the likelihood to develop PTX, CTI and PH and to define their correlation. RESULTS:PTX occurred in 306/904 cases (33.8%); CTI was required in 18/306 (5.9%). PH occurred in 296/904 cases (32.7%), and no case required treatment. Nodule-to-pleura distance (ORPTX = 1.052; ORCTI = 1.046; ORPH 1.077), emphysema (ORPTX = 1.287; ORPH = 0.573), procedure time (ORPTX = 1.019; ORCTI = 1.039; ORPH = 1.019), target size (ORPTX = 0.982; ORPH = 0.968) and needle gauge (ORPTX = 0.487; ORCTI = 4.311; ORPH = 2.070) showed statistically significant correlation to PTX, CTI and PH. Type-1 PH showed a protective effect against PTX and CTI (ORPTX = 0.503; ORCTI = 0.416). CONCLUSION:PTX and PH have similar incidence after CT-guided lung biopsy. PH along needle track may represent a protective factor against development of PTX and against PTX requiring CTI.