The ultrasonography (Mode B - Real Time) experience was analyzed to evaluate neurological diseases in children during their first year of life. Forty-two examination were accomplished in twenty-eight children with the following diagnosis: hydrocephalus (22), normal (15), subdural hygroma (3), intracranial cyst and hydrocephalus (1), giant encephalocele (1). The technique consists of positioning the transducer in the coronal, sagital and axial direction and selecting dynamically the images to be photographed. In the coronal position, the height of the lateral ventricle and the width of the third ventricule were obtained. In the axial position, the ventricular ratio-lateral ventricle width cerebral hemisphere width was obtained. Although it was a small group of patients, those indexes can objectify the ventricular size variation in children with well or poor functioning shunts. The importance of this method was the possibility to follow the development of hydrocephalus in cases of myelomeningocele and to analyze the etiology and features of hydrocephalus with or without shunts. In conclusion, this test is very usefull, mainly because it is very brief (about 20 minutes), the patient does not need sedation, it is innocuous, very precise even when compared with computarized tomography and for its low cost.