Formin-1 is the founding member of a family of genes of emerging biological and medical importance that share specific domains of homology, allowing them to be classified together as the formin homology proteins. Although deficiency mutations in formin-1 lead to profound developmental defects in limb and kidney formation, similar deficiency mutations in more distantly related members of this family (diaphanous and cappuccino in Drosophila and BNI1 in yeast) have ostensibly unrelated phenotypes. Here we describe murine and human formin-2 (Fmn2), a gene which bears a high degree of similarity to formin-1 and cappuccino. The mouse gene, which encodes a putative 1567-amino-acid open reading frame and maps to mouse Chromosome 1, is expressed almost exclusively in the developing and mature central nervous system. Expression begins at embryonic day 9. 5 in the developing spinal cord and brain structures and continues in neonatal and adult brain structures including the olfactory bulb, cortex, thalamus, hypothalamus, hippocampus and cerebellum. Human formin-2 has a similar expression pattern.