The T-box gene family encodes a large family of transcription factors with more than 20 members identified in humans so far, and homologues in many other organisms. A number of human disorders have been linked to mutations in T-box genes, confirming their medical importance. They include Holt- Oram syndrome/TBX5, Ulnar-Mammary syndrome/TBX3, and more recently DiGeorge syndrome/TBX1, ACTH deficiency/TBX19 and cleft palate with ankyloglossia/TBX22. This review describes the key features of these disorders and the involvement of T-box genes in their phenotype.