introduction Patients who underwent cardiacsurgery were usually subjected to daily chest X-rays. The ability to detect postoperative pulmonary complications using chest X-rays is limited, and this technique requires radiation exposure and consumes time.Unlike chest ultrasounography that became an invaluable diagnostic tool facilitating facilitating more accurate diagnosis of postoperative pulmonary complications. In addition, lung ultrasound is a bedside technique. . This study aims to analyze the agreement between chest X-ray and chest ultrasound. ResultsThis is an observational prospectivecohort study. 109 adult patients who underwent cardiac surgery were included. 109 patients had a chest X-ray and chest ultrasound follow-up on day 0, 66 patients had chest ultrasound and 64 chest X-ray on day 2, and 41 patients had chest ultrasound ans 44 patients had chest X-ray on day 3.In the present study the use of CXR as an Index Test For detection of Atelectasis against Ultrasound: There was a minimal agreement =0.224, 95% CI: 0.126-0.322, p<.001, with 4-15% of data that are reliable, For CRX detection of Pulmonary edema against LUS, there was a weak agreement (=0.560, 95% CI: 0.413-0.707, p<.001), with 15-35% of data that are reliable. Regrading detection of Consolidation, there was no agreement (=0.044, 95% CI: -0.061 0.141, p=.156), with 0.00-4.00% of data that are reliable. Pneumothorax detection had a weak agreement (=0.434, 95% CI: 0.026-0.841, p<.001). While CXR detection of Pleural effusion against LUS had a moderate agreement (=0.625, 95% CI: 0.523 0.726, p<.001). ConclusionFollowing cardiac surgery, lung ultrasonography found PPCs more often and sooner than chest X-ray. Our findings provide support for the idea that post-cardiothoracic surgery, ultrasonography of the lungs may serve as the principal imaging tool for the detection of PPCs, improving the quality of decision-making at the bedside. We need to find out how many PPCs are in these individuals by using lung ultrasonography as our main imaging tool.