Via LM and SEM, we studied wood structure of 51 genera representing 19 tribes of Acalyphoideae, the largest subfamily of Euphorbiaceae. Many acalyphoid woods possess the following features: growth rings indistinct or weakly defined; pores evenly distributed; simple perforation plates (but admixture of irregular scalariform plates common); alternate intervessel pits; vessel-ray pits larger than intervessel pits, circular to elongate and alternate to irregular; thin to moderately thick-walled non-septate fibre-tracheids or libriform wood fibres; parenchyma distribution diffuse, diffuse-in-aggregates, and scanty paratracheal, sometimes in thin-tangential bands; heterocellular rays seldom more than 3 cells wide; and prismatic crystals in parenchyma and /or ray cells. Within this syndrome, a number of other wood characters also occur but at lower frequency. For the most part, the unusual features have not proven systematically informative at the tribal level. Presence of lysigenous radial canals, however, supports recognition of tribe Alchorneae. Wood data do not support the segregation of Peraceae and Pandaceae from subfamily Acalyphoideae.