During febrile surveillance in the western Java City of Bandung, Indonesia, a patient with clinical symptoms consistent with hantavirus infection was found to have elevated titers of hantavirus-specific immunoglobulin M (IgM) and IgG antibodies. A subsequent epizoological investigation demonstrated a higher prevalence of hantavirus IgG antibodies in rodents trapped in the vicinity of the patient's home compared with rodents from a control area (13.2% vs. 4.7%, p = 0.036). The Old World Seoul hantavirus was detected by reverse transcriptase-polymerase chain reaction in the organs of 71% of the seropositive rodents tested. This is the first report of a Seoul virus infection in Indonesia supported by clinical, serological, and epizoological evidences. These findings suggest that hantavirus infection should be on the clinical differential diagnosis when acutely ill febrile patients report for care in western Java.