In recent years, the dimensions of different parts of the masticatory mucosa have become the subject of considerable interest in periodontics from both an epidemiologic and a therapeutic point of view. In the present article, the clinical relevance of the thickness of the masticatory mucosa for the development of gingival recessions, surgical root coverage, as well as graft harvesting will be reviewed. The concept of different periodontal phenotypes has recently been substantiated by experimental evidence using a novel, commercially distributed, ultrasonic measuring device. Based on observations made in a series of investigations, it has become clear that individuals with thin and vulnerable gingival tissue prone to the development of recession often also present with thin palatal mucosa that might not be very suitable for obtaining connective tissue of proper thickness for plastic periodontal surgery. Periodontal phenotypes are closely associated with, and are in fact an expression of, the so-called biologic width, which should be considered during subgingival placement of restorations in particular. Thus, a detailed analysis of the thickness of the masticatory mucosa may be necessary in several clinical situations.