 Methods: This is a clinical trial, a prospective, randomized study. There will be selected, consecutively, 70 patients candidates for neuraxial blocks. Patients will be randomly assigned to group A n 35, in which the antisepsis will be performed with alcohol 70, and to group B n 35, in which the antiseptic will be performed with the 0.5 chlorhexidine in alcoholic solution. Samples will be collected with swabs in an area of 25 cm2 for bacterial cultures three times: in pre-antisepsis moments, in the second minute after antisepsis, and immediately after the puncture. The number of colonies forming units per square centimeter CFU cm2 will be counted. The data will be analyzed statistically. 