To study the epidemiology of the neurologic manifestations of human immunodeficiency virus (HIV)-1 infection in Japan, we conducted two nationwide surveys. Of 1854 HIV-1 carriers, 578 had acquired immunodeficiency syndrome (AIDS) and 166 (28.7% of AIDS patients) had neurologic manifestations including HIV dementia (11.8%), myelopathy (3.6%) and peripheral neuropathy (2.6%). The incidence of neurologic manifestations in patients with HIV-1 infection through blood products was about 60% of that in patients with HIV-1 infection through sex or unknown routes. This nationwide survey showed that the incidence of neurologic manifestations in AIDS patients in Japan was consistent with that in other countries.