The objective of the research was to survey the use and medicinal applications of mamorana (Pachira aquatica Aublet) by the ribeirinhos (river dwellers) of Baixo Rio São Lourenço, Maiauatá District, Igarapé-Miri municipality, state of Pará. The target audience of the research comprises eleven (11) ribeirinhos who are older in their family nucleus, being from different families, with histories of the use of plants. We recorded nine (9) different types of indications and/or uses of Pachira aquatica Aublet, which is used for ear pain, cholesterol treatment, diabetes, scabies (“curuba”), inflammation and hematoma in the eyes, “overgrown meat” in the eyes, and conjunctivitis, in addition to being used to dye artisanal fishing nets. [ABSTRACT FROM AUTHOR]