Abstract: The present invention relates to monoclonal antibodies which recognize defined regions of the T-cell receptor (TCR). In a specific embodiment, the invention provides monoclonal antibodies which are reactive with a constant region of the alpha chain of the TCR. In particular embodiments, the invention relates to two monoclonal antibodies, termed .alpha.F1 and .alpha.F2, which react with two different epitopes on the framework region of the .alpha. monomer of the TCR molecule. In another specific embodiment, the invention is directed to monoclonal antibodies reactive with a variable region of the beta chain of the TCR. In particular, the invention provides two monoclonal antibodies, termed W112 and 2D1, which react with .beta. chain variable regions V.beta.5.3 and V.beta.8.1, respectively. In another specific embodiment, the invention is directed to monoclonal antibodies reactive with a variable region of the delta chain of the TCR. In particular, the invention provides monoclonal antibody .delta.