Electrophysiologic tests may be abnormal in asymptomatic HIV-1-infected individuals. Our study was aimed at determining whether these findings have a prognostic value and could be corrected by antiviral treatment. In 18 patients, followed for 34 or 43 months, these findings were not progressive. Only one patient developed Aids dementia complex (ADC). Three have died (one with normal, two with abnormal tests at baseline). To study the effect of antiviral treatment, another group of seven asymptomatic patients was included into a cross-over double-blind study with either eight weeks zidovudine or eight weeks placebo, separated by eight more weeks without treatment. Electrophysiological evaluation was also performed in a group of 15 patients before antiviral therapy with zidovudine or didanosine was started and again after a mean of three and 13 months treatment. Results did not suggest that treatment reverses early electroencephalographic and otoneurological changes seen in HIV-1 infection.