Harmful effects of wood dust can be divided into general toxic effects, skin deseases (e.g., eczema), and respiratory diseases (e.g., asthma). A list is presented of toxic wood species and their effects. It is recommended that wood species should be divided into three classes: toxic or allergenic; biologically active; and biologically inactive or neutral; and that the use of woods known to be harmful should be limited. <i>Mansonia altissima</i> is singled out as a particularly dangerous wood. -- AATA