In a group of 211 schoolchildren in Queensland less than 12 years of age, the mean total melanocytic nevus (mole) count was 28 (median 19), and the mean count for raised nevi was 11 (median 8). The upper aspect of the back and chest were the most commonly affected sites, with the neck being the third. Boys had significantly (p less than 0.01) more melanocytic nevi than girls, and prevalence was highest in children with pale skin and light-colored hair. Nonwhite heritage had a protective effect independent of pigmentary characteristics. Total numbers of nevi on children also were related to maternal tendency to large numbers of moles and to family history of melanoma. The only significant association observed for the presence of large (greater than 5 mm) nevi on children was a family history of melanoma. The children studied come from a general population that has the highest known risk of melanoma. In Australia they have been shown to have the highest prevalence of nevi ever reported in the prepubertal age group. These descriptive data, together with the specific pigmentary and family associations described, extend the known links between benign nevi and malignant melanoma.