A total of 23 Streptococcus gallolyticus strains, consisting of 12 strains from feces of healthy animals and 11 from clinical cases of human or cow mastitis milk, were examined genealogically. Four strains of S. bovis "biotype II/1" and 3 strains of S. equinus, the closely related organisms to S. gallolyticus, were also analyzed for outgroup comparison. Neither the amplified ribosomal DNA restriction analysis (ARDRA) nor the randomly amplified polymorphic DNA (RAPD) analysis that had been designed to recognize S. gallolyticus strains virulent in pigeons could differentiate clinical strains from the others of S. gallolyticus. No correspondence between the DNA profile in either analysis and the host animal species was detected.