Composition for application to skin comprising a biocide or combination of biocides (such as chlorhexidine, halogenated phenols, quaternary ammonium compounds； povidone-iodine； zinc pyridinethione； alcohols etc) and at least one transcutaneous vehicle (for example alkyl methyl sulfoxides, alkyl pyrrolidones, glycols, glycol ethers and glycol esters) effective to convey the biocide to a sub epidermal "resident" micro-organism. Also a method for preparing a patient for surgery comprising the step of treating an area of the patient's skin at, and in the surrounding the vicinity of, the site of an intended surgical incision with a composition effective to kill more than 93% of both "transient" and "resident" micro-organisms.
