This study investigated the prevalence of alveolar bone loss (ABL) in 5-year-old New Zealand children. The relationship of bone loss with the prevalence of caries, socio-economic status and ethnic origin was examined. Standardized bite-wing radiographs from 317 children were used to examine the alveolar bone in 1784 sites. Questionable bone loss (QBL) was evident in 8.5% of the children and definite bone loss (DBL) in 2.1%. The children with suitable radiographs had a mean dmft of 1.8 +/- 2.9 and mean dmfs of 2.7 +/- 5.0. When the children were divided into 3 groups having no bone loss (NBL), QBL only or DBL, analysis of variance on the logarithmic transformation of both the dmft and dmfs scores showed significant differences among the groups. Post hoc tests showed that the means for the DBL group were significantly different from those of the other 2 groups for both dmft and dmfs scores. Logistic regression analysis indicated that the odds ratio for having definite alveolar bone loss was slightly increased in children with a dmft of > or = 9.