Objectives<br /> To assess changes in gingival thickness (GTH) and the width of keratinized gingival tissue (KTW) following treatment with either connective tissue graft (CTG) or an albumin gel -platelet -rich fibrin mixture (Alb-PRF). Materials and methods<br /> Twenty treatment sites were included in a split -mouth design involving 10 patients with a thin gingival phenotype in the mandibular anterior region. The sample was randomly divided into two groups, with the Alb-PRF applied to the experimental group and CTG used for the control group. GTH and KTW were measured at baseline and after one, three, and six months. Results<br /> GTH increased in both groups during all follow-up periods. However, no statistically significant differences (p > 0.05) between the groups were observed at baseline and six months. At three months, the experimental group exhibited significantly higher GTH (p < 0.001). Additionally, at three and six months, the CTG group showed a superior increase in KTW (p < 0.05). Conclusion Within the constraints of this study, Alb-PRF application for modifying thin gingival phenotypes proved to be an effective therapeutic option, potentially serving as an alternative to CTGs. Although Alb-PRF resulted in thicker gingiva, CTG demonstrated a greater enhancement in KTW.