Acquired immunodeficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV) is a major global public health problem. The aim of this study is to determine the prevalence of HIV-1 infection in four municipalities of Pará State (Marabá, Parauapebas, Curionópolis, and Canaã dos Carajás), in northern, Brazil. The municipalities are located in the Carajás Complex iron mining area. The employment opportunities result in extensive migratory flow of people. A total of 4771 serum samples were obtained from 2005 to 2014 and were sent to Evandro Chagas Institute, Belém-Pará, where they were tested by enzymelinked immunosorbent assay, with reactive samples confirmed by Western blot analysis. The samples were from individuals from 23 Brazilian states and the Federal District, mainly Maranhão (39.53%) and other municipalities of Pará (34.25%). The total positivity rate was 0.48% (23/4771). The rate was 0.47% (14/2975) in males and 0.50% (9/1796) in females. Of these, 0.33% (14/ 4275) were from asymptomatic individuals whose serum were collected during the serological survey, 1.81% (9/497) were from cases featuring clinical symptoms including fever/diarrhea/jaundice, which were included in febrile, diarrheal, and icteric syndromes analyzed during the study. The findings indicated the presence of HIV-1 infection in the general population studied. The majority of cases (60.9%, 14 of 23 positive cases) were asymptomatic.