Echogenicity of the normal fetal telencephalic choroid plexus was characterized anatomically in 102 consecutive antenatal abdominal ultrasonographic examinations. Echogenicity of the plexus was observed only during the second trimester, first appearing at week 13 and disappearing after week 23. We suggest that this echogenicity may be due to different stages of glycogen chemistry in the plexus. The knowledge that telencephalic echogenicity is confined to the second trimester should help detect diseases that cause focal areas of echogenicity in fetal life.