Sea turtle fibropapillomatosis is an emerging disease characterized by a proliferation of cutaneous papillomas, fibromas, and fibropapillomas and occasional visceral fibromas. This paper aims to contribute tothe etiology of fibropapillomatosis in olive ridley sea turtles (Lepidochelys olivacea) nesting in OstionalNational Wildlife Refuge. Twenty six olive ridley turtles with cutaneous fibropapilloma were sampled and24 healthy olive ridley turtles served as controls. Biopsies were taken of the cutaneous tumors in sick seaturtles, as well as skin biopsies from control subjects, and blood samples were collected from all turtles.Tumorous samples and skin samples were microscopically analyzed in order to differentiate the histologicalfactors resulting from the disease pathogenesis, where the main histological findings were papillaryepidermal hyperplasia, orthokeratotic hyperkeratosis, spirorchid-like eggs in the dermis, and eosinophilic cytoplasmic inclusion. Hematology and blood chemistry studies were conducted on blood samples, andMCHC, heterophils, lymphocytes, monocytes, AST, total protein, albumin and globulin values were significantlydifferent between healthy turtles and turtles with tumors. A PCR test was also conducted in thesamples to determine the presence of herpesvirus and papillomavirus as possible etiologic agents, wherethe papilomavirus was absent in all the samples, while the herpesvirus was present in 69.23% of the tumors,this being the most probable etiological agent of fibropapillomatosis.La fibropapilomatosis de la tortuga marina es una enfermedad emergente caracterizada por múltiples papilomas, fibromas y fibropapilomas cutáneos, así como ocasionales fibromas viscerales. El presente trabajo tiene como objetivo contribuir a la etiología de la fibropapilomatosis en la tortuga lora (Lepidochelys olivacea) que anida en el Refugio Nacional de Vida Silvestre Ostional. Se muestrearon 26 tortugas lora con fibropapilomas cutáneos y 24 tortugas lora sanas que sirvieron de control. Se tomaron biopsias excisionales de los tumores cutáneos de las tortugas enfermas y biopsias de piel de las tortugas control, además se recolectaron muestras de sangre de todas las tortugas. Las muestras tumorales y de piel se analizaron microscópicamente para diferenciar los factores histológicos que resultan de la patogénesis de la enfermedad, donde los hallazgos histopatológicos principales en los fibropapilomas fueron: crecimiento papiliforme, hiperqueratosis ortoqueratótica, huevos de parásitos similares a espiróquidos en la capa dérmica e inclusión eosinofílica citoplasmática. A las muestras de sangre se les realizó análisis hematológico y de química sanguínea, donde los valores de CHCM, heterófilos, linfocitos, monocitos, AST, proteínas totales, albúmina y globulinas resultaron significativamente diferentes entre las tortugas sanas y las tortugas con tumores. Se realizó PCR a las muestras para determinar la presencia de genoma de herpesvirus y papilomavirus como posibles agentes etiológicos, donde el papilomavirus estuvo ausente en la totalidad de las muestras, mientras el virus Herpes se presentó en el 69.23% de los tumores posicionándose como el posible agente etiológico de la enfermedad.Sea turtle fibropapillomatosis is an emerging disease characterized by a proliferation of cutaneous papillomas, fibromas, and fibropapillomas and occasional visceral fibromas. This paper aims to contribute to the etiology of fibropapillomatosis in olive ridley sea turtles (Lepidochelys olivacea) nesting in Ostional National Wildlife Refuge. Twenty-six olive ridley turtles with cutaneous fibropapilloma were sampled and 24 healthy olive ridley turtles served as controls. Biopsies were taken of the cutaneous tumors in sick sea turtles, as well as skin biopsies from control subjects, and blood samples were collected from all turtles. Tumorous samples and skin samples were microscopically analyzed in order to differentiate the histological factors resulting from the disease pathogenesis, where the main histological findings were papillary epidermal hyperplasia, orthokeratotic hyperkeratosis, spirorchid-like eggs in the dermis, and eosinophilic cytoplasmic inclusion. Hematology and blood chemistry studies were conducted on blood samples, and MCHC, heterophils, lymphocytes, monocytes, AST, total protein, albumin and globulin values were significantly different between healthy turtles and turtles with tumors. A PCR test was also conducted in the samples to determine the presence of herpesvirus and papillomavirus as possible etiologic agents, where the papilomavirus was absent in all the samples, while the herpesvirus was present in 69.23% of the tumors, this being the most probable etiological agent of fibropapillomatosis.