Gastrointestinal obstruction is a rare complication of multiple-dose administration of activated charcoal. Previous reports deal only with obstruction after ingestion of drugs that impair gastrointestinal motility. This patient developed a small-bowel obstruction associated with the administration of multiple doses of activated charcoal (350 g, total) for treatment of theophylline toxicity. This patient also had low-grade, previously asymptomatic adhesions at the ileocecal valve. A 4.5 x 5 x 3-cm aggregate of charcoal was surgically removed from the distal ileum.