The analyses of the ectoparasite species associated with a small mammal community on Ilha Grande, a coastal island in southern of the state of Rio de Janeiro, Brazil, evaluated the level of host-ectoparasite specificity. Was used the Jaccard index for qualitative data to analyse the similarity. The lowest value of similarity occurred between Proechimys iheringi
and Marmosops incanus
and between Sciurus aestuans
and Nectomys squamipes
= 0.08) and the highest between P. iheringi
= 0.33). This index showed a low value of similarity across the ectoparasite community. The only exception from this pattern of high host specificity occurred with P. iheringi
sp., which shared five species of ectoparasites. The similarity values, for most of the cases, is smaller than 0.2.