Streptococcus agalactiae (GBS) is the leading cause of severe invasive infections in infants less than three months. Meningitis, pneumonia and sepsis are the leading cadres in these children. Infection is primarily acquired vertically from mothers colonized with GBS. GBS has many virulence factors, the capsular polysaccharide is one of the most important and are associated with different surface proteins of antigenic characteristics, such as α, β, Rib, HylB, Lmb, C5a peptidase, FbsA, FbsB and CylB which are encoded by several genes associated with virulence and host interaction acting on bacteria involved in invasiveness. The study of surface protein antigens is important for the understanding of the pathogenesis and epidemiology of infection and several these antigens have been proposed as components of multivalent conjugate vaccines. This study was carried out in order to study the molecular profiles of virulence in GBS strains. Two hundred isolates of vaginal swabs from pregnant women from Misiones (Argentina), were studied. Virulence genes those encoding: C protein (bac and bca), Rib protein (rib), laminin (lmb), hyaluronidase (hylB), c5a-peptidase (scpB), FbsA and FbsB protein (fbsA and fbsB) and β-hemolysin (cylB), were investigated by conventional PCR. Virulence genes were simultaneously identified in 73 isolates (36.5%). fbsA, fbsB and cspB genes were detected at 100% of the strains. Other genes studied were detected in these frequencies: cylB (95%), lmb (94%), bca (87,5%), rib (85,3%), hylB (81%) and bac (58%). The high frequency of detection of fbsA, fbsB and cspB genes, suggesting assessment of their inclusion in future vaccines.