The authors report the radiographic findings in 13 cases of subphrenic abscess complicating abdominaloperations at Severance Hospital, Yonsei Medical Center. Radiographic diagnosis is important because clinicalfeatures may be masked when a patient is receiving antibiotic for presumed sepsis elsewhere. 1. There were 13cases of subphrenic abscess after 670 abdominal operations (1.9%). 2. The post-operative subphrenic abscessincidence was 3.2% following gastrectomy, 2,9% after small bowel operations, 1.2% following cholecystectomy, 1.0%after appendectomy, and 1.3% each after operations on the colon and uterus. 3. The most common radiographicfindings on subphrenic abscess were pleural effusion and elevation of diaphragm or decreased diaphragmaticmovement during fluoroscopy; others include abnormal air shadow in abscess cavity, linear atelectasis in lungbase, displacement of stomach fundus or colon. 4. There were 21 pleural effusion following 670 abdominaloperations (3.1%), 10 of which occurred in patients subsequently proven by drainage to have a subphrenic abscess.