Chronic periodontitis characterized by a periodontal pocket over 5 mm, alveolar bone resorption accompanied by tooth mobility, requires periodontal surgical treatment. Conventional surgical treatment can not achieve the regeneration of periodontal tissue and thus requires regenerative procedures, such as with the addition of PRF. PDGF-BB is a growth factor that plays an important role in wound healing. Developments in additional bioactive ingredients in surgical procedures are used to regulate inflammation and increase the speed of the healing process. The purpose of this study was to determine the effect of PRF and bone graft (carbonate apatite) on PDGF-BB levels post-surgical flap in patients with chronic periodontitis. The experimental study with open label and consecutive sampling was... conducted on 10 subjects of chronic periodontitis who received surgical flap treatment with bone graft and PRF; and 10 subjects without PRF. GCF samples were collected immediately before surgery and 7 days post flap surgery for examination of PDGF-BB levels by ELISA method. The data were calculated statistically by Mann-Whitney test (p <0.05). The results showed that the mean difference of PDGF-BB level in PRF group was 9.44 pg/ml (-1.20 – 37.79 pg/ml) with p value (0.013) and Non-PRF group was 7.97 pg/ml (-6.62 - 44.42 pg/ml) with p value (0.059). The p value in the PRF group > 0.05 means a significant increase in PDGF-BB levels on the 7th day post flap surgery. Examination of PDGF levels, especially PDGF-BB, should be done in each healing phase of the wound from the inflammatory phase to the maturation and remodeling phase, for example on the 3rd, 7th, 14th and 28th days when PDGF levels approach zero and the healing process it's almost over, referring to the results of Alzahrani's research (2018) and also Matsuoka and Grotendorst (1989) which showed higher levels of PDGF-BB and VEGF in GCF on days 1, 3, 7 and 14 after surgery with minimally invasive surgery (MIS) technique. The conclusions of this study showed that the application of Platelet Rich Fibrin (PRF) and bone graft had an effect on the level of Platelet Derived Growth Factor (PDGF-BB) post-surgical flap in patients with chronic periodontitis, and elevated levels of PDGF-BB post-surgical flap with PRF application higher than surgical flap without the PRF application. Increased levels of PGDF-BB in the group applied to the PRF were higher than those that were not applied PRF, although statistically significant differences were not found, there was a tendency for the healing process of the PRF group to be better than the Non PRF group.