An adolescent girl with blond hair, her family, and classmates noted that her hair was progressively turning green. Initially the green color was thought to be secondary to chlorine from the local swimming pool. This was not the real cause. The chlorotrichosis was actually caused by an excessive amount of dissolved copper from copper pipes in the home plumbing system. Copper had leached from the plumbing and accumulated in the pipes because the rented house had been vacant for many months. Risk factors for chlorotrichosis include light-colored hair, copper plumbing, long periods when the water was not thoroughly flushed out of the copper pipes, and frequent shampooing.