Summary Ectoparasitic diseases are endemic in many poor communities in north-east Brazil, and heavy infestation is frequent. We conducted two studies to assess disease perception and health care seeking behaviour in relation to parasitic skin diseases and to determine their public health importance. The first study comprised a representative cross-sectional survey of the population of a slum in north-east Brazil. Inhabitants were examined for the presence of scabies, tungiasis, pediculosis and cutaneous larva migrans (CLM). The second study assessed health care seeking behaviour related to these ectoparasitoses of patients attending a Primary Health Care Centre (PHCC) adjacent to the slum. Point prevalence rates in the community were: head lice 43.3% (95% CI: 40.5–46.3), tungiasis 33.6% (95% CI: 30.9–36.4), scabies 8.8% (95% CI: 7.3–10.6) and CLM 3.1% (95% CI: 2.2–4.3). Point prevalence rates of patients attending the PHCC were: head lice 38.2% (95% CI: 32.6–44.1), tungiasis 19.1% (95% CI: 14.7–24.1), scabies 18.8% (95% CI: 14.4–23.7) and CLM 2.1% (95% CI: 0.8–4.5). Only 28 of 54 patients with scabies, three of 55 patients with tungiasis, four of six patients with CLM and zero of 110 patients with head lice sought medical assistance. The physicians of the PHCC only diagnosed a parasitic skin disease when it was pointed out by the patient himself. In all cases patients were correctly informed about the ectoparasitosis they carried. The results show that tungiasis and pediculosis, and to a lesser extent scabies and CLM, are hyperendemic but neglected by both population and physicians, and that prevalence rates of tungiasis and scabies at the PHCC do not reflect the true prevalence of these diseases in the community.