OBJECTIVE: Report a case of envenomation by Crotalus durissus marajoensis Hoge, 1966 in Muana, Marajo archipelago, Para State, Brazil. CASE REPORT: Fisherman, 48 years old, bitten by a rattlesnake on his right ankle when walking in the field. After the envenomation, he reported paresthesia without local pain. Then, he experienced heaviness in the head, difficulty in opening his eyes, dysarthria, blurred vision, and diplopia. He was admitted to the Municipal Hospital of Muana, 9 h after the snake bite, with the mentioned signs and symptoms, plus nausea, dizziness, difficulty in walking, and myalgia. Due to the absence of specific antivenom at the city hospital, the patient was referred to the Municipal Emergency Room in Belem, Para State, where he arrived after 18 h of the accident, presenting neurotoxic facies, mydriasis, choluria, and oliguria. The case was classified as severe envenomation, and the patient received specific antivenom vaccine. After four days, the patient with evidence of neurotoxicity was transferred to the Joao de Barros Barreto University Hospital, where clinical support and lab tests were conducted. Changes in complete blood count, coagulation test, levels of urea, creatinine, transaminases, and creatinophosphokinase were observed, showing rhabdomyolysis. Although serotherapeutic treatment and clinical support were done after a long period of time, there was an evolution towards clinical cure. CONCLUSION: The importance of early serotherapy and the rarity of such envenomation by this subspecies whose clinical features are the same as those of other crotalic accidents reported in Brazil.