The aim of this study was to evaluate beta-tricalcium phosphate (beta-TCP Cerasorb(R) Curasan-Germany) graft materials on specific parameters of rat osteoblast activity in vitro. Primary culture osteoblastic cells were isolated from neonatal rat calvaria by sequential collagenase digestion. To analyze the effect of biomaterials on cell proliferation, cell numbers and viability of the cells were cultured on the graft material for 24, 48 or 96 h. Osteoblast cells cultured in DMEF-12 media supplemented with 10% fetal calf serum were used as the control group. [H-3]thymidine was added during the last 2 h of the incubation. The cell numbers of each well were counted. Cell viability was estimated by counting the number of cells, which excluded trypan blue solution. Scanning electron microscopy was used to observe for visualizing the interactions between osteoblastic cells and TCP graft material. The proportion of cells undergoing DNA synthesis, estimated by thymidine uptake, was significantly (P<0.05) greater on the control group after the 24- and 48-h incubations. Regarding the cell numbers the difference was not statistically significant for the three time points. The number of viable cells recovered was similar for the two groups. No morphological differences were observed in cell morphology on TCP graft material and the control group. The results demonstrate that TCP graft material has no adverse effect on cell count, viability and morphology, and this material provides a matrix that favors limited cell proliferation.