As part of a wider investigation of malocclusion, the aim of this study was to determine the prevalence of gingivitis in 6-year-olds in Reykjavik. Parents and guardians of the 401 children in 8 schools were invited by letter to have their children take part. There were 230 positive replies (57%). The Gingival Bleeding Index was used to determine the condition of the gingiva on mesiobuccal and buccal surfaces of 6 selected teeth (totaling 12 surfaces). The results showed that 26% had healthy gingivae, 23% showed bleeding from one surface, 20% from two, 17% from diree, and 15% from four to eight surfaces. There were no statistically significant differences in the number of bleeding surfaces between boys and girls. The mean GBI for the whole group was 16%. Gingivitis in this group was therefore prevalent but usually slight.