The number of Streptococcus mutans, Streptococcus sobrinus, and lactobacilli in stimulated whole saliva was examined in 149 elderly persons. More than 10(6) CFU/ml of mutans streptococci were found in 57% of the subjects and 85% had more than 10(5) lactobacilli per ml of saliva. There was no difference in the prevalence of mutans streptococci between edentulous and dentate subjects whereas significantly more lactobacilli were detected in denture wearers. S. mutans was most frequent and was found in 72% of the subjects. S. sobrinus, which was carried by 44% of the persons, was found proportionally in more subjects with dentures than in dentate individuals. In most persons with S. sobrinus, S. mutans was also present but in 8% of the subjects only S. sobrinus was detected. The subjects with both S. mutans and S. sobrinus had higher salivary levels of mutans streptococci than individuals with only S. mutans or S. sobrinus.