The clinical signs of malaria in HIV patients may vary depending on the immunological status of the patient. Nationally, evidence regarding co-infection is scarce. This research describes four cases from a hospital in Iquitos, Peru, of patients diagnosed with HIV infection and a positive blood test for malaria. Two of these patients had Plasmodium falciparum infection, and two had Plasmodium vivax infection. One of the patients was in the AIDS stage with poor adherence to combination antiretroviral therapy (cART), and the other three were in the early stages and not receiving cART.