Theophylline and other methylxanthines are the strongest and most widely used antiasthmatic drugs. Mechanism of theophylline effect is complicated. The first observations of this way, depend on inhibition of phosphodiesterase by increase of cAMP what is the reason of bronchorelaxation. As a results a theophylline action we can observe induction of adenosine receptors, inhibition of the some prostaglandin synthesis or allergic reaction mediatores and decrease of the level of calcium in muscles cells. It is probably (especially in bronchial asthma or acute lymphoblastic leukemia-ALL) that the one important effect of theophylline is the some cells apoptosis. For the good results of the therapeutics effect apart of important factors deciding of the theophylline metabolism (age of patients, kind of the diet, period of menstruation and smoking), we always should consider interactions of theophylline with other drugs. In this paper we presented the most often reasons of interactions between theophylline and others drugs.