T-box (TBX) transcription factors are an ancient gene family with critical roles in embryogenesis. Currently, TBX3, TBX5, and TBX20 are TBX genes defined to have multiple protein isoforms created by alternative splicing and characterized by expression and functional studies. These proteins are important for development as mutations lead to severe developmental disorders in humans and mice. Cumulative studies suggest that alternative splicing of these genes can regulate TBX activities during multiple biological processes including cardiogenesis, limb development, and cancer mechanisms. This mini-review focuses on how alternative splicing adds complexity to transcriptional regulation of target genes controlled by TBX transcription factors. (C) 2011 Elsevier Inc. All rights reserved.