The oral distribution of Kingella oralis was investigated in 10 periodontally healthy subjects. 11 untreated adult periodontitis patients and 6 untreated localized juvenile periodontitis patients. From each subject, 6-8 each of supra- and subgingival tooth samples, 4 mucosa samples and a saliva sample were examined by culture for the presence of K. oralis. K. oralis was found in at least one oral site in 26 of the 27 study subjects, and in at least one tooth site in each of these 26 positive subjects. Its prevalence in dental plaque ranged from 23% to 59% in different subject groups. The mean percentage of K. oralis in total microbiota in the dental plaque ranged from 0.40% in the periodontally healthy group to 4.60% in localized juvenile periodontitis subjects. The organism was a significant species in a few periodontitis sites, constituting > 5% of the total microbiota.