Tumor necrosis factor-alpha (TNF-alpha) is commonly recognized as a one of the most important mediators of allergic inflammation and hyperreactivity in bronchial asthma. Several studies proved the inhibitory effect of theophylline (including it's subtherapeutic doses) on the synthesis of TNF-alpha in 24 hrs monocyte cultures. The aim of our study was to determine the influence of therapeutic and subtherapeutic concentrations of the drug on the early phase of TNF-alpha release. We showed that theophylline did not significantly alter the cytokine concentration measured by Elisa method in supernatants from 2 hrs monocyte cultures stimulated by LPS (1 microgram/ml). Therefore, we concluded that the mechanism of theophylline inhibitory action on TNF-alpha production is more likely associated with changes in genome expression, than with the inhibition of the cytokine liberation from the cell.