The therapeutic status of theophylline has changed dramatically over the last decade. As part of this change, a different view of the most appropriate therapeutic range for serum theophylline concentration (STC) has emerged. The National Institutes of Health Expert Panel Report, "Guidelines for the Diagnosis and Management of Asthma," suggests a conservative approach of aiming for STC of 5-15 micrograms/ml. This truly landmark document along with several studies in the literature, recently prompted us to change our hospital's laboratory report form for the medical record to read that the therapeutic range for STC is 5-15 micrograms/ml. We encourage hospital laboratories or other clinical laboratories who have not already made this change to do so.