Megalencephaly should be diagnosed during life, especially knowing that it could be confused with hydrocephalus. The diagnosis could be arrived at on the basis of clinical data in some cases, but mostly by way of the ventricular puncture. Pneumoencephalography or pneumoventriculography may confirm the diagnosis but it is not essential in a typical case. Other procedures like X rays of the skull, electroencephalograma or cerebral angiography are of little help. Seven cases diagnosed during life are presented. One patient had macroglossia; two brothers had a hemangioma at the glabella area. A familial tendency was noticed in two pairs of children, one of them with consanguineous parents. Judging by our series, which seems to be larger than others, megalencephaly is not such a rare condition as it is thought to be.