Diastematomyelia is a rare form of occult spinal dysraphism. It is characterized by longitudinal clefting and separating of the spinal cord by a bony or fibrous spur. Diastematomyelia is associated with other anomalies, i. e. spina bifida, scoliosis, visceral malformations or anomalies of the overlying skin. Prenatal diagnosis is based on fetal ultrasound supplemented by fetal MRI. We present a case of diastematomyelia and prenatal diagnosis in the 23rd gestational week using routine ultrasound scanning and confirmation by fetal MRI. After vaginal delivery at term, the child's development is normal. Prenatal diagnosis of isolated diastematomyelia is challenging. Management and prognosis are still controversial as only few cases have been reported. Affected fetuses might benefit from early diagnosis enabling surgical intervention before the development of neurological sequelae.