Three cases of benign myoclonus of early infancy (BMEI) were observed in the same family. Previously, only sporadic cases have been reported. Electroencephalogram (EEG) recordings were consistently normal, and the affected girls had normal neurological development. Therapy was not administered and the episodes spontaneously disappeared within the first months of life. While etiological mechanisms of BMEI are still unknown, a hereditary mechanism is now hypothesized on the basis of these cases.