Background Iatrogenic pneumothorax is a common and clinically important transbronchial cryobiopsy (TBCB) complication. A study was conducted to assess the diagnostic accuracy and clinical impact of immediate post-procedure lung ultrasound for diagnosing iatrogenic pneumothorax in patients suspected of interstitial lung disease (ILD) undergoing TBCB. Study design and methods In patients undergoing TBCB due to suspected ILD, lung ultrasound of the anterior surface of the chest was performed immediately after the TBCB procedure prior to extubation. Presence of lung point was used as a definite sign of pneumothorax. Chest radiography was routinely performed 2 h after TBCB and was used as the reference standard. Results A total of 141 consecutive patients were included. Post-procedure lung ultrasound identified definite pneumothorax in five patients (3.6%, 95% confidence interval (CI) 1.5–8.3%). Chest radiography at 2 h identified 19 patients (13.5%, 95% CI 8.7–20.2%) with pneumothorax following TBCB. The diagnostic accuracy of lung ultrasound for diagnosing pneumothorax was as follows: sensitivity: 21.1% (95% CI 6.1–45.6%), specificity: 99.2% (95% CI 95.5–100.0%), positive predictive value (PPV): 80.0% (95% CI 28.4–99.5%) and negative predictive value (NPV): 89.0% (95% CI 82.5–93.7%). Post-procedure lung ultrasound had a clinical impact in five patients (3.6%, 95% CI 1.5–8.3), of which four had a pleural drain inserted prior to extubation and one underwent prolonged observation prior to extubation. Interpretation Lung ultrasound performed immediately following TBCB has a clinical impact by identifying patients with pneumothorax in need of immediate treatment prior to extubation and by monitoring pneumothorax size in the operating room. Supplementary imaging prior to patient discharge is still needed however, as the majority of pneumothoraxes develop later in the post-procedure period.