The expression of the ATBF1 gene in developing brain was analyzed in mice from 13 days of gestation to 28 days after birth using RNase protection and in situ hybridization methods. The level of ATBF1 transcripts was the highest on embryonic day 13-15 and then progressively decreased to a hardly detectable level on postnatal day 28. Throughout the period examined, ATBF1 mRNA was expressed consistently in the basal telencephalon, diencephalon, and mesencephalon, with the highest levels in the inferior colliculus and thalamus. On the other hand, no significant expression was observed in cerebellum, neocortex, hippocampus, and olfactory bulb. These results illustrate significant regional differences in the ATBF1 expression and suggest a role of the ATBF1 gene in the formation of some specific cell populations in developing central nervous system.