Objective.Research has shown 1.5 minutes of surgical hand antisepsis with alcohol-based hand rub to be at least as effective under experimental conditions as the 3-minute reference disinfection recommended by European Norm 12791. The aim of the present study was to validate the effectiveness of 1.5 minutes of surgical hand antisepsis in a clinical setting by comparing the effectiveness of 1.5- and 3-minute applications of alcohol-based hand rub (45% vol/vol 2-propanol, 30% vol/vol 1-propanol, and 0.2% mecetronium ethylsulphate).Design.Prospective crossover trial in which each surgeon served as his or her own control, with individual randomization to the 1.5-or the 3-minute group during the first part of the trial.Setting.Basel University Hospital, Switzerland.Participants.Thirty-two surgeons with different levels of postdoctoral training.Methods.We measured the bactericidal effectiveness of 1.5 minutes and 3 minutes of surgical hand antisepsis with alcohol-based hand rub by assessing the mean (± SD) log10 number of colony-forming units before the application of hand rub (baseline), after the application of hand rub (immediate effect), and after surgery (sustained effect) so as to follow European Norm 12791 as closely as possible.Results.The immediate mean (± SD) log10 reduction in colony-forming units (cfu) was 2.66 ±1.13 log10 cfu for the 1.5-minute group and 3.01 ±1.06 log10 cfu for the 3-minute group (P = .204). Similarly, there was no statistically significant difference between the 2 groups with respect to the sustained effect; the mean ( ± SD) log10 increase in bacterial density during surgery was 1.08 ± 1.13 log10 cfu for the 1.5-minute group and 0.95 ± 1.27 log10 cfu for the 3-minute group (P = .708). No adverse effects were recorded.Conclusion.In this clinical trial, surgical hand antisepsis with alcohol-based hand rub resulted in a similar bacterial reduction, regardless of whether it was applied for 3 or 1.5 minutes, which confirms experimental data generated with healthy volunteers.