External characters enabling the sexes to be distinguished readily in the adult Anobium punctatum (Deg.), popularly known as the common furniture beetle, have been described by Kelsey & others (1945) but no account has yet been published of the external sex characters of the pupae of this Anobiid. In the course of research at the Forest Products Research Laboratory on the biology of this species, a series of larvae in the prepupal stage and of pupae have been examined to determine whether the sexes can easily be recognised in the immature stage. Sex determination, before the adult stage is reached, is of great value for expermental work on breeding techniques and other projects.