Slowly progressive hydrocephalus which needs neurosurgical intervention can present with the same clinical features as a compensated hydrocephalus which does not need treatment. Therefore no intervention is necessary for this type of hydrocephalus avoiding the high complication rate that is associated with shunt insertion in infants. Early detection of hydrocephalus is vital and a distinction between slowly progressive hydrocephalus and compensated hydrocephalus is essential.Different imaging modalities can be used for evaluation of ventriculomegaly in pediatric patients. CT scan is used to assess the overall size, shape of the ventricles, and to determine if periventricular permeation is present& the possible cause.Transcranial Doppler is reported to be accurate and reliable in detecting and grading the severity of ventricular dilatation and is ideally suited to follow up the progress of cases. Ultrasound may be also helpful in following shunt procedure particularly in the evaluation of complications and assessment of post therapeutic responses. ADC value& mapping obtained from DWI can detect periventricular interstitial edema due to transependymal resorption of cerebro-spinal fluid in hydrocephalic patients. Assessment of CSF flow indicates the potentials of using cine phase contrast MR imaging (MRI CSF flowmetry) for quantitative & qualitative CSF flow dynamics in hydrocephalus. Cine-MR for CSF flow evaluation is a useful adjunct to routine MR in the evaluation of pediatric hydrocephalus because it can assist in determining the probable level of CSF obstruction.Aim of work is to detect the types of ventriculomegaly and to differentiate between progressive hydrocephalus & compensated hydrocephalus (selection of patients for shunting), by the different imaging modalities, and when to use each modality, also in assessment of response after shunt in pediatric age group.