This is a typical condition in the intensive care unit, and the term "pneumothorax" refers to a collection of air that has built up between two pleurae, either on the parietal or visceral side, and is putting pressure on the lung. Pneumothoraxes are classified into two categories: traumatic and non-traumatic. Pneumothorax may be diagnosed in ICU patients utilising the least intrusive approaches without patient transfer by employing the standard sonographic findings in the form of lung sliding, a lung pulse, B lines and a lung point. Indications one through three are extremely indicative that there is no pneumothorax, whereas signs four through six are definitive. Our study's goal is to evaluate the usefulness of chest ultrasonography in diagnosing pneumothorax in intensive care unit (ICU) residents. Methods: A prospective study of 50 patients hospitalised to the Banha University Hospitals' critical care unit with clinical evidence or a history suggesting pneumothorax illness was done. In our research, we conducted a comprehensive history-taking, clinical examination, and investigation of each patient. A CT scan confirmed the diagnosis of pneumothorax in 42 of the patients (84 percent). 70 percent of the patients had pneumothorax discovered by ultrasound, while more than a third of the patients had pneumothorax diagnosed by chest X-ray (40 percent ). 45.2 percent sensitivity, 87.5 percent specificity, PPV of 95 percent, NPV of 23.3 percent, and an overall accuracy of 52 percent were found in the chest x-ray. An overall accuracy rate of 82% was achieved using chest ultrasonography. The sensitivity was 80%, the specificity 87.5, the PPV was 97.1, and the NPV was 46.7. On the other hand, X-ray and ultrasound were only somewhat consistent when it came to their agreement with CT scans (Kappa = 0.505). Conclusion: Compared to CT chest and CXR, lung ultrasound is an appropriate diagnostic modality in the ICU population for the detection of pneumothorax with higher sensitivity than CXR. It is simple, affordable, and the best bedside test with minimum exposure to ionised radiation.