Skier's thumb is a partial or complete rupture of the ulnar collateral ligament of the metacarpophalangeal joint of the thumb. It is an injury that rather frequently occurs in certain sports. When diagnosed incorrectly, delay in treatment can ultimately lead to chronic instability and pain. Correct knowledge of the anatomy and method of physical examination is essential when assessing a patient suspected of having skier's thumb. This article describes three different types and treatment of skier's thumb, and further describes the relevant anatomy, correct physical examination, available additional imaging and various treatments possible.