SUMMARYEighty‐three cases of dermatitis caused by wood or sawdust have been seen at St John's Hospital for Diseases of the Skin, London, in the last 20 years. The clinical details and results of patch tests are reported. The literature on dermatitis, mucosal irritation, asthma and other toxic effects of woods of some 300 botanical species is reviewed at length, with an index of scientific, trade and vernacular names, chemical formulae of the known sensitizing substances, and a table of the 28 toxic woods most often encountered. Pathogenesis, diagnosis and prophylaxis are discusse