The purpose of this study was to find out the actual condition of the imature permanent teeth, the care of imature permanent teeth and the establishment of oral health care during childhood.<BR>The subjects,4,080 children (2,015 boys and 2,065 girls) ranging from 5 to 16 years of age, were examined transversally.<BR>This report is concerned with results of an investigation into the state of plaque adherence and that of gingivitis, in particular, based on age and degree of eruption.<BR>The findings were as follows.<BR>1) The rate of mexillary anterior teeth without plaque accretion (expressed as P1T 0) tended to decrease with age among the boys and the girls as well. The rate of molars with P1I 0 tended to show a lower value compared with anterior teeth and premolars among the boys as well as the girls.<BR>2) Of all kinds of maxillary and mandibular teeth among children 16 years of age, maxillary second molars showed the lowest value for P1I 0 among the boys and the girls as well. The girls tended to show a higher value for P1I 0 compared with the boys. Teeth in the middle of eruption among the boys as well as the girls tended to show a lower value for P1I 0 compared with teeth after the completion of eruption.<BR>3) The rate of maxillary anterior teeth with normal gingiva (expressed as GI 0) tended to rise in value with age among the boys 12-16 years of age, while the rate showed almost no variations in the girls of the same age group.<BR>4) The rate of moderate gingivitis (expressed as GI 2) resulted in a higher value among the boys than among the girls. The rate for GI 2 was 8.66%,12.22% and 10.25% of central incisors, lateral incisors and canines, respectively, among the boys 12 years of age, while the rate was 10.64%,11.21% and 8.09%, respectively, among the boys 16 years of age. On the other hand, the rate for GI 2 was 3.61%,4.26% and 3.13% of central incisors, lateral incisors and canines, respectively, among the girls 12years of age, while the rate was 5.10%,6.07% and 5.08%, respectively, among the girls 16 years of age. In this manner, the girls showed a lower value for GI 2 in any age group.<BR>5) There tended to be differences in value for GI 0 between canines in the middle of eruption and those after the completion of eruption among the boys as well as the girls.