In this review, the germline genomic and cDNA structures and the evolution of the human TcR-alpha-, TcR-beta-, and Tc gamma-chain genes have been reviewed and discussed. The estimated V-gene segment repertoires established for the human TcR-alpha-, TcR-beta-, and Tc gamma-chain genes have also been summarized. The use of TcR and Tc gamma genes in the evaluation of hematopoietic malignancies and identification of chromosomal translocations has also been presented. It is hoped that such information will serve as a reference point from which the study of TcR genes can further progress. This will almost certainly include the use of TcR and perhaps Tc gamma genes in the study of the dual recognition of antigen and MHC gene products, the role of these genes in thymic education/selection, and the role(s) of these genes in oncogenesis processes and autoimmune settings.