Background: Although a role of the human cytomegalovirus (HCMV) in atherosclerosis and restenosis is probable, clinical studies are not conclusive. The present study investigates in a threedimensional (3D) human coronary transfilter co-culture model the effect of cell-free and cell-associated HCMV-infection. Methods: Human coronary endothelial cells (HCAEC) and HCMSMC were seeded on both sides of a polycarbonate filter membrane. HCMV-infection was carried out by HCMV-infected MO. As controls MO-attack without HCMV-infection, cell free HCMV-infection, and the transfilter co-culture model without MO-attack and without HCMV-infection (Mock) were used. Results: At day 1, day 4, day 7, and day 14 the effects of HCMV-infection on MO adhesion and chemotaxis and on reactive proliferation of HCMSMC was studied. Cell-associated HCMV infection of HCAEC and HCMSMC was less intense and postponed in comparison to cell-free HCMV infection. Endothelial adhesion of MO after cellbased HCMV infection was decreased in comparison to non-infected MO, no clear effect was found on chemotaxis. Both after cell-associated and cell-free HCMV infection proliferation of HCMSMC was significantly increased. Conclusions: In the 3D human coronary transfilter co-culture model both cell-free and cell-associated HCMV-infection significantly increased proliferation of HCMSMC. If we assume that HCMV is involved in the pathogenesis of atherosclereosis and restenosis, the effect of antiviral treatments should be studied in experimental and clinical studies.