Dyshormia or epileptiform spikes occurring within K-complexes have been described in patients with generalized epilepsy, with one study reporting that generalized spikes occurred frequently in association with K-complexes. We report the rate of focal epileptiform spikes occurring within K-complexes in localization-related epilepsy. Presurgical or diagnostic long-term video-EEG results of 40 consecutive patients with epilepsy (13 patients with right temporal lobe epilepsy, 20 patients with left temporal lobe epilepsy, and 7 patients with frontal lobe epilepsy) were reviewed. Sleep samples were reviewed and the numbers of K-complexes, spikes, and spikes within K-complexes were recorded. The comparison group consisted of 40 consecutive patients with nonepileptic events who were monitored with long-term video EEG. Focal epileptiform spikes occurring within K-complexes occurred in 2 of 13 (15%) patients with right temporal lobe patients, 6 of 20 (30%) patients with left temporal lobe, and 3 of 7 (42%) patients with extratemporal lobe epilepsy. In most patients, spikes occurring during K-complexes were rare. We identified spikes occurring during K-complexes in patients with localization-related epilepsy. The sharply contoured components of K-complexes or associated sleep spindles may obscure focal spikes within K-complexes. Nevertheless, K-complexes may be associated with focal epileptiform discharges.