INTRODUCTION: Many clinical studies have shown ultrasonography (US) is useful for the diagnosis of different abnormalities involving pleura; chest ultrasound (CUS) is widely used to detect pneumothorax in patients, but there is no data on its use for the follow-up of lung re-expansion after lung resection. MATERIALS AND METHODS: We performed a unicentric observational study all patients between January 2018 and May 2021 undergoing lobectomy in which lung re-expansion was assessed daily with chest ultrasound (CUS) and chest radiography (CXR) until chest drainage was removed. Ultarsound clinical signs indicating a pneumothorax were: the detection of a positive lung point, absence of sliding or a consistent stratosphere sign with an absence of lung pulse, B-lines, I-lines or consolidations. RESULTS: Sensitivity, specificity, PPV, NPV of CUS and CXR were, respectively: 86% vs. 98% (p = 0.002); 100% vs. 100% (p = 1.0); 94% vs. 75% (p = 0.231); and 94% vs. 99% (p = 0.7). CONCLUSIONS: Ultrasound is a method available also to the patient’s bed, an easy-to-learn technique even for inexperienced operators, therefore it is a valuable tool for checking the post-lobectomy lung expansion, reduce the use of chest radiography.