Radiological exams are often ordered but go unscheduled, which can delay diagnoses and lead to other medical errors. In this retrospective study at one academic institution, the clinical necessity of 700 unscheduled radiologic examination orders (100 from each of seven different radiographic modalities) was examined. Study results indicate that, except for CT, obstetric ultrasound and fluoroscopy radiologic tests, the majority of unscheduled orders are clinically necessary and that 7% of all radiologic examination orders remain unscheduled a month or more after the order was placed.