Standardized samples were taken from the skin of 100 patients immediately before and after their hip operation. 50 patients were-operated with and 50 patients without use of plastic drapes. The samples were evaluated quantitatively and qualitatively by the employment of usual microbiological methods. The statistical analysis revealed that at the end of the operations there were a) as many microbes on the drape as on the skin where no drape had been used and b) many more microbes under the drapes than either on them or on undraped skin. The value of the plastic drape as a means of preventing infections has to be doubted. Discontinuing the use of plastic drapes seems to be justified.