Cathartic colon is an infrequent and severe manifestation of chronic irritant laxative abuse. Little is known of its natural history after cathartics are stopped. Previous reported cases have shown residual roentgen abnormalities on follow-up examinations. A case is presented of cathartic colon caused by more than 70 years of laxative abuse that demonstrated complete reversal of the roentgen changes four months after stopping the medication. Some pathophysiologic correlates of this dramatic reversibility are discussed.