A two month observational study was carried out during March and April of 1997. In the services of surgery and ginecology of the Hospital Dr. R.A. Calderon Guardia to evaluate the antibiotic prophylaxis in patients with clean and clean-contamined surgery, determining the percentage of nosocomial surgical wound infection. The data shows an index of surgical wound infection of 3.79% versus 1%, the accepted gold standard for this surgery; there was also a high porcentage of wrong prophylaxis in spite of an adecuate indication, the percentage of correct prophylaxis was signifcantly lower.