AbstractThe aim of this investigation was to study the periodontal status at the ages of 15 and 20 years in the same individuals. Gingival and periodontal data from 100 adolescents in 1973 constituted the basic material. Eighty subjects could rereexamined in 1978. The mean number of teeth per subject was 27.1 both in 1973 and in 1978. Three individuals in 1973 and two in 1978 had no bleeding gingival units. There was a decrease between 1973 and 1978 in the number of subjects with a high number of inflamed gingival units. The buccal and lingual surfaces also showed lower prevalence of gingivitis, while the proximal surfaces showed a slight increase in prevalence. The prevalence of surfaces with plaque in 1978 was decreased for buccal and lingual surfaces but slightly increased for proximal surfaces. Sixty‐six individuals in 1973 and 71 in 1978 had no pocketing. Altogether 75 tooth surfaces with pocketing were diagnosed in 1973 and 21 in 1978. Most of the pockets were located at the proximal surfaces of the molars. Four individuals with infra bony defects in one to two sites were found in 1973 and five in 1978. No progression of the bony defects found in 1973 seemed to have occurred during the 5‐year period. In spite o(the frequent proximal areas with gingivitis, very few 20‐year‐olds showed signs of marginal bone loss, which indicates that gingivitis does not necessarily lead to destructive periodontitis in young