Purpose: This cross-sectional study was performed to determine whether an association exists between the width of keratinized mucosa and the health of implant-supporting tissues. Materials and Methods: Data on 200 dental implants were collected. Periodontal parameters measured included Plaque Index, Gingival Index, width of keratinized mucosa, thickness of keratinized mucosa, radiographic bone level, and bleeding on probing. Statistical analysis was accomplished with the t test, Wilcoxon rank sum test, and logistic and linear regression models. Significance was established when P was less than .05. Results: The mean Gingival Index score, Plaque Index score, and radiographic bone loss were significantly higher for those implants with a narrow zone ( 2 mm) of keratinized mucosa. Implants with a narrow zone of keratinized mucosa also were more likely to bleed upon probing, even after adjusting for Plaque Index, smoking, thickness of the gingiva, and time since implant placement (adjusted odds ratio, 2.37; 95% confidence interval, 1.04 to 5.83). Significant independent association also was found between the width of keratinized mucosa and radiographic bone loss in favor of wider zone of keratinized mucosa. Conclusion: Increased width of keratinized mucosa around implants is associated with lower mean alveolar bone loss and improved indices of soft tissue health. (Cross-sectional Study) Keywords: dental implants, keratinized gingiva, peri-implant tissues