The present author has studied 70 epileptic cases whose majority were diagnosed as cryptogenetic epilepsy and whose seizures of grand mal type appeared in their early childhood, by recording as many EEG of their near relatives, parents and siblings, as possible, from the genetical and clinical points of view. Results are as follows:1) In 8.3% of patients' near relatives history of epileptic seizure was found while in 9.5% of them history of infantile convulsion was found; in these cases there was no statistically significant difference between parents and siblings. The percentages appear a little higher than ones in similar studies made by other authors. In the present communication, the former figure may favorably compare with the incidence of epileptic disorders among near relatives of patients with epilepsy that appeared in their young childhood, and the latter one may compare with the incidence of infantile convulsion among blood relatives of patients with febrile spasm and kindred disorders. Above all, the history of infantile convulsion was frequently found among parents of those who had the first attack before two years of age.2) Paroxysmal abnormality in EEG was revealed in 54.6% of patients' parents, and the incidence was higher in mothers than in fathers. Of 70 patients,61 had parents of whom both or either one presented some sort of paroxysmal abnormality in EEG. However, only 16.7of parents who presented EEG abnormality had clinical seizure of epileptic nature. In case of probands with focal EEG abnormality, paroxysmal abnormality in EEG was more frequently found in parents of female probands than in those of male probands and also more frequently in cases which were attacked under five years of age than in the other cases, but there was no significant relationship of proband's seizure type and EEG finding to the incidence of EEG abnormality in their parents else. Therefore, study on the significance of paroxysmal patterns which appear so frequently in parents' EEG should be left for future resolution.3) Incidence of familial history as to convulsive disorders was 55.7%, of which 34.3% was history of epileptic disorders and 32.9% was that of infantile convulsion, and preeminently high in comparison with the results reported by other investigators. It may be attributed to the deviation of the patients group partly due to the selection of cases and partly due to the method of investigation.4) As concerns correlation between proband's intrafamilial abnormality, patients who had been attacked before two years old had histories of convulsive disorders, particularly infantile convulsion or kindred disorder of epileptic nature relatively frequently in their family. Furthermore, there was a tendency towards frequent revelation intrafamilially, and there were many cases both of whose parents had either one of convulsive disorders or paroxysmal abnormalities in EEG, or who had history of convulsive disorders in both of paternal and maternal sides. There were many cases which present convulsive disorders not only in probands but also in their siblings. Beside age of onset, there was no significant relation of proband's sex, seizure type and EEG findings to incidence of familial hystory of convulsive disorders.5) As compared parents who have paroxysmal EEG abnormality and their lineage with parents who have no EEG abnormality and their lineage, epileptic disorders were much more frequently in the former (23.6%) than in the latter (5.0%), and there was a tendency for a more frequent revelation in the former, while infantile convulsion had no noticiable difference of the incidence between them. (Author's abstract)