A case of prenatal diagnosis of Sturge-Weber syndrome associated with polymicrogyria is reported. The diagnosis was based on a unique association with unilateral hemispheric gyriform calcification, focal hemispheric atrophy and white matter changes on prenatal imaging including ultrasound and MRI. Polymicrogyria, which is exceptionally associated with Sturge-Weber syndrome, is suggestive of and reinforces the hypothesis of early impairment of the cerebral microvasculature related to leptomeningeal angioma, which may lead to abnormal cerebral development as early as the second trimester of pregnancy.