Bronchiolitis obliterans organizing pneumonia (BOOP) is a syndrome with distinct clinical, radiological, and histological features. The radiographic changes of BOOP vary from multiple patchy, alveolar, or ground‐glass infiltrates to diffuse reticulonodular opacities. The most frequently observed CT features are areas of lung consolidation and ground‐glass opacity often with a subpleural distribution and small nodules; in addition, bronchial wall thickening and bronchodilatation can be seen. The exact pathogenesis of BOOP after organ transplantation remains to be clarified. Some researchers have suggested that BOOP is a non‐specific reaction to injury; rejection is the most common injury in lung and kidney transplant recipients.