Theophylline poisoning long has been recognized as difficult to treat and still has an over-all mortality rate of about 10%. In recent years, the increasing use of sustained-release preparations has changed the pattern of toxicity. The management of theophylline toxicity is compounded by clinical differences between chronic (overmedication) intoxication and acute single ingestions of a large amount of the drug, inter- and intraindividual variability in theophylline metabolism and dose-dependent kinetics in poisoned patients. Management decisions should be based on both clinical assessment and laboratory information (particularly theophylline concentrations).