Enumeration of a one hectare plot at 900 m a.s.l. in Papua New Guinea revealed 693 individuals of 228 tree and liana species ≥ 10 cm DBH. A 0.1 hectare subplot contained 302 individuals of 106 species 2.5 ≤ DBH < 10 cm. Lauraceae Moraceae and Myristicaceae were the most important families in both size classes. This site is very diverse compared with other tropical forests and like other species-rich sites worldwide it has high aseasonal rainfall and high rates of natural disturbance.