Alloplastic bone graft materials such as beta-tricalcium phosphate (beta-TCP) have become a viable alternative to current mainstream therapies in dentistry such as allografts and autogenous grafts. Analyzing their potential as a vehicle to deliver growth factors is therefore an important step in determining their clinical efficacy. The positive mitogenic and chemotactic effects of platelet-derived growth factor (PDGF) on bone cells have been well documented. Objectives: It was the aim of these studies to adsorb PDGF to beta-TCP to examine the osteogenic properties of the modified matrices, and to study the time course of PDGF release from beta-TCP. Methods: 125I radiolabeled PDGF was incubated with beta-TCP, and the amount of 125I-PDGF adsorbed and subsequently released was measured using a gamma counter. Proliferation of human osteoblastic cells, obtained from alveolar bone was assessed by 3H thymidine incorporation. Results: The greatest significant increase (p<0.05, ANOVA) in PDGF adsorption occurred between 1 and 5 minutes, indicating that binding takes place rapidly. PDGF was released from the beta-TCP in an initial burst, which was followed by a slow and steady release over the remaining time. After one hour, 16% of the PDGF had been released. After 10 days (240 hours), only 45% was released. There was a statistically significant difference (p<0.05, ANOVA) between the measured percent release at 1 hour compared to 24 and 240 hours. Cells incubated with PDGF-treated beta-TCP showed significantly (p<0.05, ANOVA) greater proliferation than with beta-TCP alone. Conclusions: The results demonstrate that while PDGF adsorption to beta-TCP occurs rapidly, it is released from the matrix in a controlled, time-dependent manner. This study further suggests PDGF enhanced the effects of beta-TCP on bone cell proliferation, and that this combination offers potential as a treatment for bone regeneration.