Synopsis A general survey of odour generation in the axillae is given, with particular reference to the role of topically applied antimicrobial agents in odour suppression. A new apparatus is described which will allow a rapid and reliable quantification of in vivo antimicrobial action and which may be usefully employed in optimization of individual systems to achieve effective deodorancy. Findings are presented on the antimicrobial efficacy of deodorant compositions and correlated with practical olfactory studies.