Objective: To compare the clinical outcomes of the tunnel technique (TUN) combined with either thin connective tissue graft (C.T.G.) (TUN + thin C.T.G.) (1 mm) or thick C.T.G. (TUN + thick C.T.G.) (2 mm) for the treatment of localized gingival recession (G.R.).Material and methods: Twelve patients, with 24 maxillary localized type RT1 GR were randomly assigned into two groups. Clinical, esthetic, and patient-reported outcomes were evaluated at baseline and at 6month follow-up.Results: The TUN+thin C.T.G. group showed a higher mean G.R. reduction (1.53± 0.66) (primary outcome variable) than the TUN+thick C.T.G. group (1.44± 0.89), but no statistically signi cant difference was detected at the 6-month follow-up (p=0.77). No statistically signi cant differences were found between TUN+thin C.T.G. and TUN+thick C.T.G. concerning complete root coverage (C.R.C.) (58.3% versus 41.7%, respectively), gingival ticknness (G.T.) or Root-coverage Esthetic Score (R.E.S.) at 6 months. Regarding patient-reported outcomes, both groups reported having experienced similar pain at 7 days (p>0.05). No statistically signi cant differences were found between the groups in the analysis of the aesthetic score.Conclusion: Both treatments showed a similar reduction in G.R. In addition, similar C.R.C., G.T., R.E.S., pain and self-reported esthetics were achieved in both groups.Clinical relevance: Application of thin CTG provided a similar result than thick CTG for the treatment of RT1 localized GR.