The local success of protected areas for effective biodiversity conservation depends largely on ensuring the integration of local communities and the persistence of wildlife species and ecological processes. We investigated the perceptions of riverine residents living around a sustainable-use protected area towards giant otters (Pteronura brasiliensis). Between March and December 2011, we conducted 41 interviews with riverine residents in the region of the National Forest of Amapá (AP, Brazil). These interviews revealed a strong negative attitude towards giant otters, highlighted by recent reports of otters being killed in 12.2% of the interviews. Generalized linear models showed that years of education and age weakly predicted attitudes towards otters in the study area (i.e., respondents with the longest time in education and older were less likely to dislike otters and to consider giant otters as damaging income or fishing activities, respectively). These results suggested that to conserve giant otters in this region efforts should focus on environmental education and long-term research projects.