Periventricular pseudocysts are important sequelae of different noxious insults in the developing brain. Accurate diagnosis of those pathologic entities during early life has therefore become of direct concern to the clinician. When present at birth, they suggest an intrauterine pathology. It has only been with the advent of real-time cranial ultrasonography that subependymal cystic lesions can be detected antemortem. 25 infants were postnatal diagnosed in ultrasound as having periventricular cystic lesions. They belonged to different pathological entities: focal paraventricular pseudocysts (5 cases), periventricular leukomalasia (6 cases), polycystic encephalomalacia (1 case), subependymal pseudocyst (9 cases), connatal viral infection (3 cases), and chromosomal abnormality (1 case). Sequelae of noxious insults in fetal life appear clearly different to those after perinatal injury. Ultrasound findings should be interpreted in combination with obstetric history. Some obstetric complications during 2. trimester can cause paraventrikular cystic formation in fetus. Neurotrophic viral infection and chromosomal abnormalities have also been implicated to produce cystic lesions in this region. This work implies that a wide variety of intracranial pathology is found in newborns with periventricular cystic lesion. Those lesions are not a terminal event in infant, but may be a condition of major clinical importance for further neurologic development.