The complete primary structure of the cDNAs encoding the alpha and beta chains of the T-lymphocyte receptor for antigen from a human alloreactive, cytotoxic T-cell clone, L17, is presented. Sequence analysis of these genes reveals that both are related to immunoglobulins and are composed of variable, diversity (at least in the case of the Ti beta clone), joining, and constant region sequences. Comparison of the sequence of the alpha-chain cDNA to that of previously sequenced mouse and human alpha cDNAs suggests the presence of human T-cell receptor alpha D-region sequences. Southern blot analysis confirms the finding that these cDNAs represent the functional receptor genes expressed by the L17 cytotoxic T-cell clone. The availability of these full-length T-cell receptor cDNA clones from a human T-lymphocyte clone of known antigen specificity should allow an analysis of the relationship between T-cell receptor structure and function.