Topography and fine structural organization of coxal organs and anal organs are compared in pleurostigmophorous chilopods. Each of the coxal or anal pores leads into a cuticle-lined pore channel, the bottom of which is surrounded by a single-layered epithelium. The epithelium is composed of different cell types, except for the larval anal organs of Lithobius forficatus. The main epithelial cells show a fine structure like transport-active cells with enlargements of the cell surfaces, plasmalemma-mitochondrial complexes and a widened subcuticle. The main epithelium is surrounded by junctional cells, exocrine glands, and the cells of the pore channel. A distinct mucous layer, containing mucopolysaccharides, covers the specialized cuticle of the transporting epithelium, and is secreted by the exocrine glands. The entire epithelium is separated from the hemolymph by an inner cellular sheath. In Lithobius forficatus the coxal organs transport Na+ ions into the hemolymph, resulting in an increase of the Na+ ion concentration. On the other hand, the coxal organs of L. forficatus are also capable of absorbing water vapour from the atmosphere. An analogous function is assumed for the similarly structured coxal organs and anal organs of other chilopods.