It is universally recognized that an epidural catheter may be misplaced in the subarachnoid space or a vein, with aspiration and test dose administration designed to detect these situations. However, subarachnoid blockade may result even when these tests are correctly performed, implying that subdural catheter misplacement may occur. In addition, other epidural anomalies may also result from such subdural placement. The authors list and give clinical examples of situations in which they trace potential consequences of epidural catheter passage via a subdurally placed needle.