The Zic genes are a family of zinc finger transcription factors defined by their homology with the Drosophila gene, odd-paired (opa). Zic2 has a critical role in forebrain development, as is evidenced by the fact that, in both mice and humans, diminished expression results in the severe forebrain malformation known as holoprosencephaly. Published information indicates that Zic2 expression is most prominent in the dorsal neural tube/spinal cord and in the hindbrain; however, there is no published description of the pattern of expression of Zic2 in the developing forebrain where the main Zic2 associated phenotype occurs. Using a Zic2-specific antiserum, we present new information about the expression of Zic2 in the developing mouse forebrain. In addition, we show that in sonic hedgehog (Shh) null mice, the expression of Zic2 is expanded ventrally in some structures while absent in others, suggesting that Shh has a role in regulating the expression of Zic2.