Troponin T (TnT) is a component of the troponin complex which regulates muscle contraction in response to alterations in intracellular calcium ion concentration. In human heart, multiple isoforms of cardiac TnT have been described on the basis of antibody studies and molecular cloning of corresponding cDNAs. These isoforms are all derived from the transcription of a single gene, TNNT2, located on chromosome 1q32, and generated by alternative splicing. We show here that isoform diversity is achieved by the use of both alternative exons and alternative acceptor sites and present the organisation of the human TNNT2 gene, which is composed of 17 exons spread over 17 kb. A potential structure of the promoter region is also presented. Several polymorphisms in both the exonic and intronic regions were identified, some of which may act as modulators of the expression of this gene.