Whether or not keratinized tissue is needed around dental implants to maintain peri-implant health is a controversial subject. To clarify this issue a search was conducted for clinical trials that appraised the significance ofkeratinized gingiva (KG) around teeth and dental implants. A critical assessment of the data revealed that the literature is replete with studies that contradict one another with respect to the need for KG as it relates to survivability of implants, gingival response to plaque, inflammation, probing depths, recession, and loss of bone. When groups of patients with and without KG were compared with respect to various clinical parameters, a statistically significant better result in the presence of KG could be interpreted to indicate that having KG is advantageous. However, quantitative differences between groups with and without KG were usually very small. Overall, the data was interpreted to indicate that some patients may need augmentation of keratinized tissue to maintain peri-implant health. Ultimately, the decision to augment KG is a judgment call that needs to be made by the treating clinician, because there are not enough data to facilitate development of definitive guidelines relevant to this subject. Apparently, the need for KG is patient specific, and at present there is no method to reliably predict who would benefit from tissue augmentation.