In order to study the incidence and variations of the suprapatellar septum, 100 knee joints of 50 neonatal cadavers were examined anatomically. In 26 % of the neonatal knee joints, a complete septum was found. Perforated septa with different shapes and residual septa were seen in 64% knees. A complete involution of the former septum was found in 10 of our cases. A suprapatellar septum combined with a mediopatellar plica was found in 18 knees. © 1994 Springer-Verlag.