Abstract:Frequencies and species of oral yeasts were examined in two groups of normal young females in three trials of isolation at intervals of one to three weeks by using a mouth-swabbing method. One group consisted of 78 students of a dental hygiene school (referred to as DH group) and the other group comprised 31 students of a nurses' training school (NT group) in Niigata. In the DH group, the average percentage of yeast-positive subjects was 29 in the three trials of isolation, and 69 isolates in total were recovered from 30 of the 78 subjects. Sixty-one (88%) of the 69 isolates were identified as Candida albicans. Fifteen (19%) of the 78 subjects were positive for oral yeast in all of the three isolation trials performed. In the 15 subjects, C. albicans was found during the experimental period. In the NT group, the average percentage of yeastpositive subjects was 41 and a total of 38 isolates were recovered from 17 of the 31 subjects. Thirty-two (84%) of the 38 isolates were identified as C. albicans. Oral yeasts were isolated from 9 (29%) of the 31 subjects in all of the three trials of isolation and C. albicans was recovered from 8 of the 9 subjects. These findings indicate that C. albicans is the most dominant species among oral yeasts and is a stable inhabitant in the mouth of normal young females.