Amplitudes of contingent negative variation (CNV) in 40 migraine patients were studied during the pain-free period and compared with healthy controls (n = 24). The early component (initial CNV) is especially more negative in migraine patients. Within the migraine group, 14 children with migraine without aura (mean age 13.6 years) were compared with 11 healthy children (mean age 12.4 years). Migraine children differ from healthy children in the same manner that adult migraine patients differ from healthy adults. The CNV of five healthy children did not differ from the CNV of their siblings suffering from migraine. We suggest that there is a family-related cortical hypersensitivity which does not necessarily lead to the development of migraine.