Background:The aim of this study was to compare thick versus thin connective tissue grafts (CTG) for the treatment of gingival recession, over a 3-month period.Methods: Forty-two CTG procedures were performed on single tooth Miller Class I or II recession defects at either premolar or anterior sites in 30 individuals. Procedures were randomized (1:1 ratio) to CTG thickness of 1 or 2 mm (parallel group design). Primary outcomes were the change in the width of the zone of keratinized tissue and the amount of root coverage achieved 3 months postoperatively at the recipient site. Secondary outcomes included change in the thickness of keratinized tissue at 3 months and patient-reported outcomes, such as pain, bleeding, and swelling at both the recipient and donor sites at 1 week, 2 weeks, 1 month, and 3 months.Results: No significant differences were found between the two groups for any of the primary or secondary outcomes. Mean root coverage achieved was 2.1 ± 0.2 mm in the 1-mm thick group and 2.5 ± 0.2 mm in the 2-mm thick group (P = 0.33).Keratinized tissue width was increased by 2.2 ± 0.2 mm in the 1-mm thick group and by 2.7 ± 0.3 mm in the 2-mm thick group (P = 0.18). Keratinized tissue thickness was increased by 1.0 ± 0.1 mm and by 1.2 ± 0.1 mm in the 1-and 2-mm thick groups, respectively (P = 0.09).Conclusion: Within the current study limitations, our results suggest that similar root coverage and increase in the width and thickness of keratinized tissue can be achieved at 3 months whether a 1-or 2-mm thick CTG is used. K E Y W O R D Sgingival recession, patient reported outcomes, randomized clinical trial, tissue grafts 966