Periventricular leucomalacia (PVL) is the most common form of hypoxemic brain damage in infants. In PVL, there is usually a preceding history of asphyxia or hypoxia. This results in hypoxic-ischaemic damage to the region of the brain around the lateral ventricles, a particularly vulnerable area as it is in a border zone between arterial supplies. PVL is usually first recognised as an echodense heterogenic flare in the anterior and posterior periventricular areas on brain ultrasound scan. This must clearly be differentiated from the typical halo seen in newborns. The formation of pseudocystic periventricular lesions is typically seen after 2 weeks. Thereafter, PVL is characterized by ventricular asymmetry with irregular walls or by cerebral atrophy. Age-specific neurological ultrasound findings are rarely seen in patients with PVL. As these individual developmental stages of PVL cannot always be found by ultrasound scan, the following criteria for diagnosis are recommended: Increased intense and heterogenic echodense areas followed by a breaking up of these echodense areas in the anterior and posterior periventricular regions on brain ultrasound scan. Multiple and thick-walled, initially non-communicating periventricular pseudocysts. Persistent typical asymmetrical dilatation of ventricles with irregular and blurred ventricular walls.