Objectives: The purpose of this study was to evaluate the influence of leukocyte- and platelet-rich fibrin (L-PRF) on impacted mandibular third molar (IMTM) extraction wound healing, patient postoperative discomfort, and incidence of alveolar osteitis. Method and Materials: Thirty-four patients (20 female, 14 male) who met the inclusion criteria for this split-mouth randomized clinical trial were enrolled and 30 patients completed the study. Patients were randomized and underwent bilateral IMTM surgical extractions. Following extraction, one socket randomly received L-PRF, and the other socket served as a regular blood clot control. Postoperatively, the soft tissue healing index (HI), pain according to visual analog scale (VAS), facial swelling using a horizontal and vertical guide, and incidence of alveolar osteitis were evaluated 1, 3, 7, and 14 days after surgery. Results: Sites treated with L-PRF resulted in improved HI (P = .001) and lower pain VAS scores (P = .001) in the first postoperative week. Significant reduction of facial swelling was recorded on first (P = .035) and third (P = .023) postoperative days in L-PRF sites versus controls, ceasing to nonsignificant difference at day 7 (P = .224). None of the L-PRF sites and four control sites were affected by alveolar osteitis (P = .001). Conclusion: Within the limitations of this split-mouth study, L-PRF improved soft tissue healing and reduced postoperative pain, swelling, and incidence of alveolar osteitis after IMTM surgical extractions. Palabras clave: impacted tooth, pain, platelet-rich fibrin, third molar, tooth extraction, wound healing