Visceral leishmaniasis (VL) is an anthropozoonosis with high prevalence and incidence in the Northeastern region of Brazil. This study aimed to determine whether people living near the Mossoró River in the city of Mossoró, Rio Grande do Norte, have knowledge of VL and to characterize the environmental properties of this region. Questionnaires were administered to 478 residents in three neighborhoods near the Mossoró River, addressing the population’s knowledge about VL and environmental characteristics. Most survey participants were female, with ages between 18 and 40 years, 53.8% had completed primary education, and 61.5% owned pet dogs (p < 0.05). The majority (95.9%) showed little knowledge about the characteristics inherent to sandflies, and 85.3% were unaware of the environments preferred by this vector (p < 0.05). Sewage from the homes of respondents was mainly dumped into the river (44.6%), and 76.6% of the respondents complained about the accumulation of garbage in the streets (p < 0.05). The association between education and knowledge about the transmission of VL and preferred vector locations was statistically significant (p < 0.05). The lack of knowledge in the population about VL and the residential environment indicates a risk of maintaining sand fly habitats and hence disease transmission.