The most common complication during sinus graft surgery is tearing or perforation of the Schneiderian membrane. Perforations are most likely to occur if the sinus membrane is thin. Preoperative prediction of the antral membrane thickness may be of practical importance during maxillary sinus augmentation procedures. The purpose of this investigation was to analyze a possible association between gingival phenotypes and thickness of the healthy sinus mucosa.Twenty consecutive patients without preoperative anamnestic, clinical, or radiologic signs of maxillary sinus pathologies were enrolled in the study. During otorhinolaringologic surgical interventions, maxillary mucosal biopsy specimens were endoscopically obtained from the sinus floor, and gingival thickness was measured at the maxillary anterior teeth.Eleven out of 20 individuals had thick gingival tissues, and the remaining 9 presented with thin gingival phenotype. The average thickness of the Schneiderian membrane was 0.97 +/- 0.36 mm with a wide inter-individual variability. Thickness of the sinus mucosa amounted to 1.26 +/- 0.14 mm in individuals with thick gingival architecture and 0.61 +/- 0.15 mm in subjects with thin gingival tissues. The association between thickness of the antral mucosa and periodontal phenotypes was statistically significant (P < .0001).Gingival thickness seems to represent a reliable parameter to predict sinus membrane thickness. Further investigations are needed to support these preliminary data.