Occasional staff or visitors to operating theatres are usually requested to don over-shoes as this is perceived to reduce bacterial floor colony counts. However, this entails some expense and considerable inconvenience. Using disposable surface contact plates floor bacterial counts were measured four times a day at five different sites during the 5 normal working days of one 2-week period in a general operating theatre when over-shoes were worn and one 2-week period when over-shoes were not worn. There was no significant difference in the mean bacterial floor colony counts between the two periods according to sampling times or sites. As in Intensive Therapy units, over-shoes should no longer be used in general operating theatres.