The highly active antiretroviral therapy (HAART) can cause peripheral neuropathy. In this study, the impact of specific substances of HAART on neurocognitive function during HIV infection was measured. Event-related potentials (ERP) from patients receiving (HAART) with ddl, ddC, or d4T were compared to a control group without any of these three substances. More patients suffering from neurocognitive disorders and peripheral neuropathy were found in the patients receiving ddl, ddC, or d4T (p >= 0.01). Patients treated with ddl, ddC, or d4T showed a significant increase of the latency of the P3 component (p >= 0.02). In accordance to the literature, these results indicate that ddl, ddC, and d4T represent an additional factor in the development of HIV associated neurocognitive disorder besides the HIV infection itself. It is assumed that these alterations are induced by the toxic impact of ddl, ddC and d4T on gamma-polymerase of the mitochondrias in the central nervous system.