SUMMARYMHC class II molecules and self antigens, such as Mls, influence T‐cell selection by clonal deletion of potentially self‐reactive T cells. In order to examine the role of various class II molecules in the T‐cell receptor‐self antigen interaction, class II transgenic and recombinant mice were analysed for TCR expression. Our studies indicate that the Aα and Eα chains can present Mls gene products for the clonal deletion of Vβ6‐bearing T cells, and that theAαqchain is defective in this process. We have also shown that Eα Aβ heterodimer in transgenic and recombinant mice is expressed and functions to delete I‐E reactive Vβ11 T cells, demonstrating again the role