Two types of pre-operative skin preparation were compared in a prospective randomized study conducted on 100 patients undergoing elective surgery: 51 patients were shaven (group I) and 49 were prepared with a depilatory agent. In all cases skin preparation was performed on the eve of the operation. Bacterial density, measured immediately before surgery by application of a contact agar preparation was 493 +/- 928 CFU in group I and 386 +/- 670 CFU in group II (NS). Bacterial density was less than 25 CFU in a significantly greater number of group II patients (P less than 0.01). On the second postoperative day, the number of scars without any sign of sepsis was significantly greater in group II patients (P less than 0.05). In addition, the depilatory agent proved bactericidal against 3 pathogenic strains (S. aureus, Pseudomonas aeruginosa and E. coli). Depilation with a chemical agent seems to be a satisfactory method of pre-operative skin preparation. It is more rapid than shaving, it can be applied to areas not easily accessible to razors, and it can often be carried out by the patient himself.