Objective The purpose of this study was to evaluate the effect of biologic characteristics of platelet-rich plasma (PRP) and platelet-rich fibrin (PRF ) on proliferation and differentiation of rat osteoblasts. Study design Blood samples were collected from 14 healthy volunteers (7 male) with a mean age of 23.2 ± 2.24 years. PRP and PRF were prepared with standard protocols. The exudates of PRP and PRF were collected at the time points of 1, 7, 14, 21, and 28 days. The levels of platelet-derived growth factor AB (PDGF-AB) and transforming growth factor β1 (TGF-β1) were quantified in PRP and PRF. Then the exudates of PRP and PRF were used to culture rat calvaria osteoblasts. The biologic characteristics of osteoblasts were analyzed in vitro for 14 days. Results PRP released the highest amounts of TGF-β1 and PDGF-AB at the first day, followed by significantly decreased release at later time points. PRF released the highest amount of TGF-β1 at day 14 and the highest amount of PDGF-AB at day 7. Exudates of PRP collected at day 1 and exudates of PRF collected at day 14 expressed maximum alkaline phosphatase (ALP) activity, though no significance was shown. Cells treated with exudates of PRF collected at day 14 reached peak mineralization significantly more than both negative control and positive control groups. PRF is superior to PRP, from the aspects of expression of ALP and induction of mineralization. Conclusions PRF released autologous growth factors gradually and expressed stronger and more durable effect on proliferation and differentiation of rat osteoblasts than PRP in vitro.