The optimization of seeding and culturing of human osteoblast-like cells on three collagen-based biomaterials (bovine, equine and calf collagen membrane) was studied by cell proliferation and cell colonization (scanning electron microscopy) analysis. Osteoblasts of five patients were seeded onto the three biomaterials and two different parameters were varied: the time intervals between initial seeding, and adding culture medium (2 h, 6 h, 12 h, 24 h) and the seeding corceini-ation (1 x 10(5), 1 x 10(6), 2 x 10(6) cells/ml) ofcclls onto biomaterials. The results of the study demonstrated that the time interval between seeding osteoblasts and adding Culture medium as well as the seeding concentration effects the cell proliferation and the cell colonization. The best proliferation rate was achieved by adding the culture medium 2 h after initial seeding and with a seeding density of 1 x 10(5) cells/ml. Moreover, all three biomaterials resulted in different proliferation rates. The best proliferation rate resulted with the bovine collagen membrane. In Conclusion, the examined parameters are very important for the development of the tissue engineering techniques and in a larger perspective also for reconstructive surgery. (C) 2002 Elsevier Science Ltd. All rights reserved.