A survey of 308,101 schoolchildren conducted in 10 of 11 states in Peninsular Malaysia revealed that 10.7% have Pediculus humanus capitis infestation. The results of treatment with 1%, 2% and 5% DDT in coconut oil in 374 cases reveal cure rates of 3.5%, 15.8% and 51.3%, respectively, suggesting that the head louse has probably developed resistance to this insecticide in Malaysia.