Melanocytic nevus density in 378 Asian and 68 Indo-Pakistani school children 6 to 18 years of age was compared with that in 1146 white children of the same age range. At all ages, the number of melanocytic nevi 2 mm or larger per square meter of body surface area was substantially lower in Asians and Indo-Pakistanis than in white persons. Among white persons characteristics associated with a higher risk of cutaneous melanoma in adults, that is, light skin color, a propensity to burn rather than tan in the sun, and a history of numerous or severe sunburns, are also associated with the highest melanocytic nevus density in children. Examination of these same host pigmentation and sunburn factors among Asian children revealed no association with nevus density.