A 50-year-old man with positive test for human immunodeficiency virus (HIV) by enzyme-linked-immunoassay and Western-blot, without clinical manifestations of acquired immunodeficiency syndrome (AIDS), developed acute polyradiculoneuritis and was treated by plasmapheresis with improvement. We believe that chemical homologies of antigenic determinants between HIV and P2 protein of peripheral nervous system and myelin basic protein may induce crossed-reaction, thus developing acute polyradiculoneuritis and central nervous system involvement, respectively. The nervous system involvement hy HIV also occur in the HI-viremy, seric conversion alone, and AIDS with or without oportunistic infections.