A 29-year-old medical resident awoke with intense pain in his right shoulder after spending several hours playing tennis on the Nintendo Wii video game system. A diagnosis of "Wiiitis" or inflammation of the tendons from overuse of the Wii controller was made. The patient was treated with ibuprofen and told to abstain from playing Wii games, and he recovered fully. Physicians should be aware of the risk of muscle injuries from intensive use of new gaming systems like the Wii.