The aim of this study was to examine the superoinferior extension of the post-levator aponeurosis fat pad in the upper eyelids of Japanese cadavers. Twenty-six upper eyelids (12 right and 14 left) from 15 Japanese cadavers (6 men and 9 women; average age at death, 82.1 years) were used in this experimental anatomical study. After an orbital exenteration, the tissues were cut sagittally through the center of the orbit, and the superoinferior extension of the post-levator aponerosis fat pad was microscopically examined on the sections. Consequently, the fat pad superiorly reached the myotendinous junction between the levator aponeurosis and the levator palpebrae superioris (LPS) muscle in 17 eyelids with the nonbranching LPS muscle. The fat pad extended to the roots of the superior and inferior branches of the LPS muscle in the other 9 eyelids with the branching LPS muscle. Inferiorly, the fat pad was limited to the conjunctival fornix in 13 eyelids, but reached the tarsal plate in the other 13 eyelids. This study showed anatomical variation in the superoinferior extension of the post-levator aponerosis fat pad in Japanese cadavers.