Of 1270 schoolchildren (651 girls and 619 boys) from 33 urban and rural primary schools in different regions of Kenya who were examined for head lice, 17.1% were infested (8% with living lice or nits, 9.1% with dead nits). The over-all difference between infestation rates in urban and rural schools was not significant, but there was considerable variation in the five different regions selected. Infestation was not sex-related. Infestation rates tended to be higher in older children and in children with longer hair. Negroid children had lower infestation rates than non-Negroid children. The criterion seems to be hair type. Prevalence of infestation was higher in private schools because non-Negroid children predominate in these schools. There was no correlation between infestation and the sharing of a towel or comb, but infestation tended to be higher in those who wash less, in those who share their bed, and in those who sleep with room-mates. Levels of infestation were low, with most harbouring only one or two lice.