The frequency of clinical infection of the vaginal vault after hysterectomy was compared in two groups of patients, a study group treated with povidone-iodine vaginal pessaries for 36 hours pre-operatively and prepared with povidone-iodine preparations at the time of operation, and a control group given no preliminary treatment and prepared with chlorhexidine preparations at the time of operation. No significant difference was demonstrated between the two groups. Vault infection occurred in 32% of the entire series of patients (severe infection 14%) and infection correlated with the presence of pathogenic bacteria in the vagina. No significant differences in bacterial colonisation of the vagina between the two groups were demonstrated at any stage of the investigation. Preliminary preparation of the vagina with povidone-iodine pessaries is not recommended.