Head lice are small parasitic insects adapted to living mainly on the scalp and neck hairs of their human host. They are mainly acquired by direct head-to-head contact with an infested person’s hair. Domestic animals are not vectors of lice infestation. A female louse lives 2 or 3 weeks and may deposit about ten eggs each day which are glued to a hair. In one third of cases itchiness is the only symptom, and it is due to individual hypersensitivity to lice saliva. Diagnosis can be made by careful scalp inspection after having wet the hair and combed it with a fine tooth comb (“nit comb”). Treatment include the application once (or twice 7 days apart) of shampoos, lotions or gels containing insecticides (pyrethrins, synthetic pyrethroids or organophosphates). Resistance to one insecticide is possible and requires to change to another agent.