Mesothelial cells (MC) obtained from the human omentum are a good alternative to the use of endothelial cells (EC) as a covering for vascular prostheses of polytetrafluoroethylene (PTFE), given the antithrombogenic properties and good behavior in vitro of mesothelial cells. We studied the behaviour of mesothelial cells seeded on PTFE prostheses with an interposed fibroblastic matrix for seeding. The mesothelial cells were extracted from 30-40 g fragments of human omentum by enzymatic digestion with collagenase. The cells extracted were seeded onto small disks of PTFE to which a matrix composed of fibroblastic cells had been fixed with 5% glycerol after the fibroblasts reached convergence. Interposition of a fibroblastic matrix fixed with glycerol notably improved the adherence of the seeded mesothelial cells and the stability and durability of the cell layer formed on the prosthetic surface. The effectiveness of seeding mesothelial cells was confirmed by labelling the cells with 111In-oxine. This showed that once the cell layer had formed (24 h after seeding), the fibroblastic matrix favoured the maintenance of a stable layer of mesothelial cells 4 hours after uptake of the radioactive substance.