Over the last decade, several authors have described an early negative (Ne) and a later positive (Pe) potential in scalp event-related potentials (ERPs) of incorrect choice reactions. The aim of the present study was to investigate the intracerebral origin and distribution of these potentials. Seven intractable epileptic patients participated in the study. A total of 231 sites in the frontal, temporal, and parietal lobes were investigated by means of depth electrodes. A standard visual oddball paradigm was performed, and electroencephalogram (EEG) epochs with correct and incorrect motor reactions were averaged independently. Prominent, mostly biphasic, ERP complexes resembling scalp Ne/Pe potentials were consistently observed in several cortical locations after incorrect trials. The most consistent findings were obtained from mesiotemporal structures; in addition to P3-like activity found after correct responses, an Ne/Pe complex was generally detected after incorrect trials. The Pe had a longer latency than the P3. Other generators of Ne/Pe-like potentials were located in different regions of the frontal lobe. The latency of the Ne was shortest in parietal, longer in temporal, and longest in frontal regions. Our findings firstly show that multiple cortical structures generate Ne and Pe. In addition to the rostral anterior cingulate cortex, the mesiotemporal and some prefrontal cortical sites seem to represent integral components of the brain's error-checking system. Secondly, the coupling of Ne and Pe to a complex suggests a common origin of Ne and Pe. Thirdly, the latency differences of the Ne across lobes suggest that the Ne is primarily elicited in posterior and temporal, and only later in frontal regions.