Zic genes comprise a family of transcription factors, characterized by the presence of a zinc-finger domain containing two cysteines and two histidines (C2-H2). Whereas the embryonic expression patterns of Zic1, 2, 3, and 5 have been described in detail, Zic4 has not yet received close attention. We studied the expression of Zic4 by in situ hybridization during mouse embryogenesis. Zic4 mRNA was first detected at low intensity at embryonic day (E) 9 and, by E10.5, expression was up-regulated in the dorsal midline of the forebrain with a strong, expanded expression domain at the boundary between the diencephalon and telencephalon, the septum, and the lamina terminalis. The choroid plexus of the third ventricle expresses Zic4, as does the dorsal part of the spinal neural tube, excluding the roof plate. The dorsal sclerotome and the dorsomedial lip of the dermomyotome also express Zic4 whereas dorsal root ganglia are negative. At E12.5, Zic4 continues to be expressed in the midline of the forebrain and in the dorsal spinal neural tube. Postnatally, Zic4 is expressed in the granule cells of the postnatal day 2 cerebellum, and in the periventricular thalamus and anterior end of the superior colliculus. We conclude that Zic4 has an expression pattern distinct from, but partly overlapping with, other members of the Zic gene family.