This study examined the curve of Spee, the anatomic curve formed by the buccal cusp tips of posterior teeth from the canine to the second molar, in the maxillary and mandibular dental arches of 50 healthy young adults. The mean radius of the curve of Spee was 106.4 mm in the maxilla and 83.4 mm in the mandible. The mean depth was 1.6 mm in the maxilla and 1.9 mm in the mandible. The curve of Spee was significantly flatter in the maxilla than the mandible but did not differ between males and females. Understanding the curve of Spee is important for dental reconstruction and developing proper occlusion.