Thirty-seven infants whose cerebral real-time B-mode ultrasound (CUS) documented hyperechogenic areas in the thalamus and basal ganglia (HTBG) either of linear or fine punctate pattern, were studied prospectively by color Doppler imaging (CDI). This study aimed to establish a relationship between these areas and the regional vasculature, to analyze associated disorders to establish pathogenesis, and to determine clinical significance. HTBG were diagnosed in the first 4 days of life in all but 7 infants. Different patterns of HTBG were observed: punctate in 11 infants, linear in 12, and mixed in 14. The basal ganglia were affected in all patients, 9 also had involvement of the thalamus. CDI confirmed that HTBG were allocated along the gangliothalamic vessels. Blood flow velocity waves were obtained at this level in all patients. Real-time spectral analyses were performed in 35 patients and compared with a control group of 20 healthy neonates. Differences were not significant. Computed tomography and magnetic resonance imaging failed to indicate this abnormality. Necropsy revealed basophilic deposits in the walls of involved arteries. Congenital infections manifested in 5 patients, chromosomal abnormality in 1, dysmorphic syndromes in 9 (3 unidentified), isolated congenital defects in 5, and diverse congenital disorders in 3. In the remaining 14, no congenital disorders nor infections were found. This CDI study demonstrates the vascular location of these HTBG. Supported by early CUS diagnosis, it is speculated that vascular injury in that region has a prenatal origin. This abnormality does not appear to alter regional blood flow. HTBG are associated with very heterogeneous disorders and in most patients the etiology and pathogenesis remain unclear.