Shock, seizures, cardiac arrhythmias, and respiratory and cardiac arrests developed in a patient who ingested 8.5 g of theophylline. Her condition improved and her serum theophylline concentration decreased from 170 to 20 mg/ml during six hours of charcoal hemoperfusion. Theophylline was removed from the serum by the uncoated charcoal column, as shown by an extraction efficiency approaching 100%. The maximum charcoal clearance of theophylline was 163 ml/kg/hr. The average endogenous theophylline clearance in adults is 50 ml/kg/hr and that achieved with hemodialysis is only 24.3 ml/kg/hr. Uncoated charcoal efficiently removes theophylline from the serum; charcoal hemoperfusion should be considered in severe theophylline toxic reactions. (JAMA240:474-475, 1978)