A clinical investigation of povidone-iodine alcoholic solution on disinfectant efficacy at the operative site was carried out in comparison with poloxamer-iodine alcoholic solution and povidone-iodine aqueous solution. Bacterial samples obtained by the cylinder scrub method from 10 cm2 of abdominal skin pre- and post-disinfection were filtered using a millipore membrane and cultured aerobically at 37 degrees C for 48 hours. The antimicrobial efficacy of each product was expressed as the logarithmic reduction value (reduction factor) in resident bacterial counts. Significantly higher reduction factors (RF) of the total resident bacteria were obtained with povidone-iodine ethanol solution (RF 2.02) than with povidone-iodine aqueous solution (RF 1.17). No adverse reaction was observed with either preparation during the study period. It is concluded that povidone-iodine ethanol solution is a reasonable and effective antibacterial agent for pre-operative skin preparation.