Group B Streptococcus (GBS) is the most frequent cause of early onset of neonatal sepsis. Case-fatality rate is 6-20% for newborns. Neurological sequel occurs in 30% of survivors. In 1996, the Centers for Disease Control and Prevention (CDC), the American College of Obstetricians and Gynecologists, and the American Academy of Pediatrics recommended that obstetrics providers should adopt either a culture-based or a risk-based approach for the prevention of this disease. The aim of this prospective study was to determine the colonization rate of GBS in our population of pregnant women between July 1st 2001 and December 31st 2002, and to introduce a culture-based strategy to prevent early onset neonatal GBS disease. From a population of 1756 pregnant women, 1228 were screened with rectal and vaginal swabs (69.9%). Maternal colonization rate was 1.4% (17 patients). There was one case of early-onset neonatal sepsis consistent with GBS disease (0.6%) in a patient with negative cultures. From the colonized patients, only one presented risk factors. Because most of the colonized women did not present intrapartum risk factors, the results of this study suggest that the culture-based approach should be used for the prevention of early-onset GBS disease in our population. Cost-benefit studies are needed in our country to determine if this prevention strategy is able to be implemented in all the settings of Argentina.