Recent observations in asthmatics demonstrated anti-inflammatory and immunomodulatory activities of theophylline besides the bronchodilating effect. Theophylline inhibits the mediator release from mast cells, peripheral blood monocytes and alveolar macrophages. The proliferative response of T-cells as well as the influx of eosinophils in BAL fluid is inhibited by treatment with theophylline. The production and release of pro-inflammatory cytokines are affected by theophylline showing a potent inhibitory effect on the production of IL-1beta, TNF-alpha and IFN-gamma. The production of the anti-inflammatory cytokine IL-10 is increased. Evidence is mounting that the anti-inflammatory effects and immunomodulating actions are exerted at lower plasma concentrations than those required for bronchodilation. These activities are of relevance in the treatment of chronic obstructive pulmonary disease (COPD), a disease in which the inflammatory component is considered to be more important than previously thought.