An examination has been made of the secondary wood of available species of the genus Nothofagus B1. From the results it appears that on the basis of wood anatomy a ready separation can be made into two distinct groups within the genus: one comprising the New Guinea species (eight examined) and the other the temperate species from South America, New Zealand, and eastern Australia (14 examined). The New Guinea species can be separated easily from the remainder by the larger, less numerous vessels, the distinct bands of parenchyma, and the absence of tracheids. The results support the segregation of the New Guinea species into a separate subsection of the genus as proposed by van Steenis (1953).