A white Italian boy, aged 5 years and 8 months, is reported with failure to thrive, hypotonia, truncal ataxia, psychomotor retardation, and congenital horizontal pendular nystagmus with only waves I and II on auditory brainstem responses. Our patient's clinical picture resembles that previously reported in 10 male Oriental patients. He did not manifest spastic diplegia by the age of 2 years, as did the subjects reported in the literature, but knee-jerk hyperreflexia was evident at the most recent clinical reevaluation. Serial brain MRI studies revealed a cystic brain lesion and peritrigonal hyperintensities with no brainstem abnormalities. To date, no other child with a similar syndrome has been described either in Europe or in America. The clinical features of this condition are consistent and characteristic. A definitive diagnosis is achieved by demonstrating the absence of all waves following wave I or wave II on auditory brainstem responses as early as 3 months of age. Due to the predominance of males, the occurrence in siblings, the early age at onset, the non-progressive course, and the characteristic auditory brainstem response findings, the syndrome may have a genetic origin and be attributable to a dysgenetic brainstem lesion.