polystyrene treated with 1.25% NaCl (toxic control). Cell counts, cell death detection assay, and a cell activity assay (XTT, a tetrazolium-based colorimetric assay) were performed after 3, 6 and 9 days. Urothelialcell seeded-PTCO films (0.5 × 10 6 cells/cm 2 ) were implanted into the subcutaneous space of athymic mice for up to 12 weeks and unseeded PTCO polymers were implanted as a negative control. RESULTSThe urothelial cell adherence rates on the polymers were similar to those for glass and polystyrene. The cell activity (XTT assay) was higher in cells seeded on the polymers than in cells seeded on polystyrene and glass after 3 and 6 days. There were no significant differences between the apoptosis rates of all groups at the given sample times, except for the high levels in the toxic control. In vivo the urothelial cells survived on the polymers for 12 weeks with no adverse reactions in any of the mice. CONCLUSIONSCO-alkene polymers are biocompatible materials for urothelial cells in vitro and in vivo , and thus are potential biomaterials for the urogenital tract.