Electrophysiological studies were done to investigate the value of EEG and evoked potentials (AEP, VEP, SEP) in detecting CNS affections in HIV-infected children staged P0-P2 (CDC-classification). Among 90 EEGs from 38 patients only 5 showed slowing of background activity (from 4 patients of the P2-group). In 38 AEPs of 27 patients staged PI and P2 we found prolongation of interpeak-latencies only in the P2 group (7 of 20 patients). Late onset of AEP was found in the P1 (4/7) and the P2 (2/20) group. 37 VEPs in 26 P1/P2 patients were abnormal (peak latency and amplitude) in 2 of 7 (P1) and in 4 of 19 (P2) patients. SEP (25 from 22 P1/P2 patients) showed an amplitude reduction of the cortical potential (N20) only in 2 of 6 P1 patients, 16 P2 patients had normal results.Electrophysiological investigations can be helpfull in detecting CNS affections before the appearance of clinical symptoms, but in the most cases the pathological findings are unspecific and neurological deterioration can occur despite normal findings.