Current Japanese asthma guidelines recommend theophylline as an additional regimen to inhaled beta-agonists (on demand use) and inhaled corticosteroids (beclomethason dipropionate 200-1200 mu g/day or fluticason propionate 200-800 mu g/day) for patients whose asthma is not controlled completely. Similar recommendations are made in the International Consensus Report on Diagnosis and Treatment of Asthma. Recent advances irt the understanding of its actions, especially regarding the antiinflammatory and immunomodulatory effects of low doses of theophylline, encourage its appropriate use in asthma treatment. Furthermore, asthma and chronic obstructive pulmonary disease (COPD) are considerably common diseases, and the economic benefits associated with the use of a relatively inexpensive, once or twice daily oral drug (intravenous infusion, if necessary) could be of importance. But, because of its narrow therapeutic range, dosage must be individualized bt order to optimize the treatment based on the measurement of theophylline concentration in serum. Theophylline is an old medication with new forms. When used effectively and safely it can have significant clinical benefits for patients. This paper intends to review the effectiveness of theophylline-historically and contemporarily. (C) 2000 Prous Science. All rights reserved.