A case of a patient who developed an intestinal perforation secondary to a charcoal stercolith is reviewed. The case involves a young female on methadone maintenance who received multiple-dose charcoal therapy for an amitriptyline ingestion. Peritoneal signs developed several days after admission, and an exploratory laparotomy was done. A perforation measuring 4 cm in diameter was found in the posterior wall of the sigmoid colon. A 120-gm obstructing charcoal mass was found at the site of the perforation. Previous reports of intestinal obstruction secondary to charcoal inspissation are noted, and case similarities are discussed. All reported cases of charcoal obstruction involve the administration of multiple-dose-activated charcoal in the treatment of ingestions of medications known to have antiperistaltic activity. With a rare potential of mechanical obstruction, the decision to use repetitive-dose charcoal therapy should be made judiciously when the ingested toxin or coincident therapeutic medications have antiperistaltic activity.