By subtractive cDNA hybridizations, we have isolated a new species of T-cell receptor cDNA clone whose predicted amino acid sequence has homology to variable, constant, joining and diversity segments of immunoglobulins and T-cell receptors. The corresponding genomic sequence is also rearranged in several T-cell DNAs. The four potential N-linked glycosylation sites, frequency of expression and predicted molecular weight (27,800) of this molecule make it a likely candidate for the α-chain of the T-cell receptor. Expression data also indicate that this gene may be activated at a later stage of T-cell differentiation than the β-chain.