The neutralization technique by reducing the number of plaques (NRNP) for detecting antirabic antibodies in personnel at risk was used. Serum samples from individuals at high risk and from persons with vaccination antecedents and without them were studied. The neutralization technique was compared with the biological technique in mouses and as a result of the study it was obtained a concordance of 100%. It was found that sex does not influence on the response of the antibodies to this virus, although the direct contact and the number of times that the individual has received the vaccine act positively on the immune response. The introduction of this technique in the laboratory allows to have a useful tool for the follow-up of the personnel receiving the vaccine before and after being exposed to the rabies virus.