Summary The efficacy and safety of povidone-iodine (PVP-I) and 60% v/v% n-propanol on the forehead of patient's were examined using a newly developed method. Significantly higher reduction factors (RFs) of the total resident flora were obtained using PVP-I immediately after and 3–6 h after application (1·4, 1·4, 1·4) than with isopropanol (0·6, 0·6, 0·8) using the detergent scrub method. No significant difference was found using the cyanoacrylate method. Propionibacter spp. showed similar results. With Staphylococcus epidermidis, RFs of 1·8 were obtained with both bath agents using the detergent scrub method, but using the cyanoacrylate method significantly higher RFs were obtained with isopropanol immediately and 3 h after application (1·3, 1·3) than with PVP-I (0·4, 0·5). This phenomenon seems to be due to the limit of complete elimination of the resident bacterial counts in vivo.