Electric source imaging (ESI) using high-density scalp EEG with at least 128 channels has been reported to accurately localize interictal epileptiform activity. The precision of ESI with 10–10 electrodes has been debated. In a pilot study of 10 patients with well defined epileptogenic lesions (focal cortical dysplasia N = 4, tumor N = 2, unspecified N = 2, cavernoma N = 1, proliferative oligodendroglial hyperplasia N = 1) with focal epilepsy (4 frontal, 2 temporal, 1 parietal, 1 temporoparietal, 1 temporooccipital) we used the presurgical routine of 37–41 scalp electrodes (10–10 system, including inferior electrodes F11, F12, P11, P12) for the source analysis of interictal epileptiform potentials with BESA-Research and for coregistration with the individual MRI (BESA-MRI). 9–209 spikes were averaged (mean: 65.9, median: 21, range 9–209; no spikes in 1 patient with FCD so that no source analysis was possible). The location of ESI was 0–1 cm to the lesion in 8 patients, 3–4 cm to the lesion in 1 patient. ESI shows promising results also with a presurgical routine scalp EEG electrode placement. Prospective studies with lesional epilepsies could further define the precision and reliability of this protocol (Plummer et al., 2008, Mégevand et al., 2014).