Up to now, pulsed field gel electrophoresis (PFGE) has been used successfully for the analysis of the chains of infection of multiresistant staphylococci, enterococci and other germs involved in hospitalism. The purpose of this study was to find out whether yeast isolates from mothers and those from their newborns differed in genotypes. In this investigation, 103 parturient mothers and their children were examined for colonization by yeasts in sampling the vaginal secret at delivery and by taking swabs from the oral mucosa and the anus of the children on the third day after parturition. The samples were cultured on Sabouraud glucose agar and incubated for 48 hrs at 37 degrees C. The differentiation of the isolates was done biochemically by means of the VITEK-AMS system and morphologically on rice-extract agar. Subsequently DNA-fingerprinting analysis was carried out. In 6 cases we could prove the presence of Candida spp. in the mothers as well as in their children. In all cases the strains from mother and child showed the same banding pattern. Likewise, the strains isolated out of the vaginal secretion and the vaginal epithelium of individual women were identical. The differences observed between strains isolated from various women were of low or medium degree. This shows the PFGE to be an efficient procedure to demonstrate the relation of strains derived from mothers and their newborns.