The piriform aperture is an anatomical structure generally pear-shaped, formed by some facial bones. The knowledge of its morphological presentation is of significant importance for performing a surgical procedure. This study aimed to analyze the morphometry and shape of the piriform aperture in human skulls, considering the sexual dimorphism of this structure. One hundred (100) human skulls were evaluated. The measurements were made with a digital caliper rule. Two parameters were analyzed: the height of the piriform aperture (R-ANS) - distance between the bottom edge of internasal suture to the anterior nasal spine; width (PA-W) - the longest distance in a transverse plane. Its form was evaluated according to seven types described in the literature and the sex differentiation (based on the Vanrell frame). For data analysis between sexes, we used the Student's t-test (p<0.05; CI: 95 %). In this study it was observed that the height (R-ANS) of the piriform aperture in males (31.4 mm) was higher than in females (29.4 mm), without significant differences. The width (PA-W) had equal means values for both sexes (25.7 mm). Regarding the shape of the pyriform aperture, it was found that the type I (pear) is the most common in males (43.6 %) and in women the type VII (rounded) is the predominant type (36 %). When sexes were evaluated in a combined manner, it was observed that the most common was the type I (pear - 39.1 %) and the less common were type III (diamond - 0.0 %), type II (inverted heart - 1.6 %) and type IV (inverted heart - 3.1 %). Knowledge of these morphometric data and piriform aperture formats is essential for surgical procedures involving this anatomical region. The results, particularly those related to the shape of the piriform aperture in women, may contribute to future work related to this facial structure, leading to better surgical decisions.
