Clinical follow up and complete neuropathological examination was made on seven cases of multicystic encephalomalacia of infancy. Etiological factors were carefully studied in all the cases. They consisted of prenatal injuries presenting as a cord prolapse, in 3 cases; prolonged labour with marked cyanosis; abdominal trauma during gestation, and various maternal infections at different stages of pregnancy. Pathological interest is centred on the variable involvement of different areas of the brain, generally sparing the cerebellum and brain stem, and being minimal or absent in the occipito-temporal areas. This distribution may be explained by a different effect of the "causal agency" on these different areas, or by a different capacity of these regions to react against injury. Among the etiological factors reviewed in the literature, the anoxic theory appears the most probable, as there was a close parallelism between lesions and vascular areas, mainly the carotid and vertebro-basilar systems.