The possible influence of the food and fat content of meals on the bioavailability and pharmacokinetics of a 350 mg sustained release theophylline (CAS 58-55-9) preparation (Bronchoretard) was investigated after single dose oral administration to 18 volunteers in a randomised 3-way crossover design. The treatments investigating administration of the test preparation in a fasting state, after a standard meal and after a high-caloric fat evening meal, according to commonly applied rules, were shown to be equivalent with respect to the extent of bioavailability (AUC) and the observed maximal concentration (Cmax). Pharmacokinetic parameters describing sustained release characteristics were not changed to any relevant degree. As expected, the co-administration of food resulted in a physiologically determined delay in absorption, which is probably not therapeutically relevant during long-term administration.