Wrist arthroscopy has become an accepted diagnostic technique, and it is starting to be a useful therapeutic tool. Extensor tendons, the radial artery, and dorsal sensory nerve branches are at risk of injury during this procedure; however, understanding periportal anatomy should make wrist arthroscopy safer. Wrist arthroscopic portals were established in 19 fresh cadaver wrists, after which the limbs were dissected and periportal anatomy was described and quantified. The 1-2, 6R, and 6U portals were the most perilous, while the midcarpal, 3-4, 4-5, and distal radioulnar joint portals were relatively safe. Even "safe" portals had occasional adjacent sensory nerve branches and tendons. A safe technique of establishing wrist arthroscopy portals is emphasized.