We sought to prospectively identify the role of neurosonography in the evaluation of a consecutive group of small-for-gestational-age (SGA) neonates, and also to identify the association of neurosonographic findings with cocaine exposure and cytomegalovirus (CMV) infection. Neurosonographic imaging was performed in 180 SGA neonates within 72 hours of birth. Urine samples were screened for CMV and cocaine metabolites (CM) in all cases. Sixty-five neonates (37.5%) had an abnormal neurosonographic appearance. Nine neonates were positive for CMV and 31 neonates were positive for CM. Focal echolucencies (27), ventricular dilation (27), and subependymal hemorrhages (12) were the most common neurosonographic abnormalities. The first two were more common with CM (p < .05). An abnormal neurosonographic pattern was seen more often in SGA neonates with CM (54.8%, 17 of 31; p < .05) and CMV (67%, 6 of 9; p < .01) as compared with the rest (32.6%, 44 of 135; p < .01). Among those without CM or CMV, prematurity was associated with an increased risk for abnormality (p < .001 between groups), specifically subependymal hemorrhage, ventricular dilation, and porencephalic cysts. Five CMV-positive neonates showed periventricular, echogenic foci mainly in the area of the frontal horn. Two new findings with SGA were caudate nucleus echogenicity and a "moth-eaten" appearance of the thalamus, each found in three infants. Neurosonographic imaging is useful in the evaluation of SGA neonates. Focal echolucencies and caudate echogenicity suggest maternal cocaine use, and periventricular echogenic foci strongly suggest fetal CMV infection.