Formerly, the Picrodendraceae formed the subfamily Oldfieldioideae within the Euphorbiaceae. The introduction discusses the taxonomy, wood and pollen morphology. Only four genera are present in Malesia. Three of them are either monotypic (Kariothamnus) or comprise only a single species (Choriceras and Petalostigma) in New Guinea. Austrobuxus (three species) is the only widespread genus in Malesia. The taxonomic treatment contains descriptions, keys, drawings and notes on distribution, ecology, etc.