LIM-kinases, including LIMK1 and LIMK2, are unique LIM-family proteins with two tandem LIM motifs at the N-terminal and a serine/threonine kinase domain at the C-terminal. In this study, we cloned two types of mouse Limk2 cDNA; one is an intact form (Limk2a) and the other has only one complete LIM domain (Limk2b). Northern blot analysis showed Limk2a mRNA was ubiquitously present in various adult tissues, while Limbk2b was predominantly expressed in brain. We also identified genomic organization of the Limk2 gene; it is similar to that of the related gene Limk1. The transcription unit contains 16 exons plus two alternative exons, thus, variation in the initiator exon usage gives rise to alternative transcripts of Limk2. Fluorescent in situ hybridization analysis showed the Limk2 gene were mapped to mouse chromosome 1D. These findings provide some important clues to the in vivo functions of LIM kinases.