Pentoxifylline (PTX), a non-specific inhibitor of cAMP phosphodiesterases, is commonly used for treatment of peripheral vascular disorders although its direct action on endothelial cells is not well described. The aim of this study was to determine the influence of PTX on tubule formation and mRNA expression for angiogenesis-related proteins in endothelial cell line C166 and mouse proepicardial explants cultured on collagen. C166 cells and explants were stimulated with proangiogenic cocktail containing bFGF/VEGF-A/VEGF-A and with proangiogenic cocktail enriched with PTX. After stimulation the number and morphology of tubules stained with anti-CD31 antibody was examined under a confocal microscope and expression of mRNA for VEGF-A, VEGF-B, VEGF-C, bFGF, IGF-1, Dll4 and Notch1 was measured with RealTime PCR. In C166 cell line there was no significant difference in tubule formation and mRNA expression, but in proepicardial explants we observed a considerable reduction in tubule number and in mRNA levels for Dll4 and Notch1 after PTX administration. In conclusion, PTX indirectly inhibits angiogenesis in mouse proepicardial explant cultures but has no significant effect on C166 endothelial cell line.