The TCR complex is a multisubunit complex, comprising at least eight transmembrane units. The clonotypic TCR α and β chains are responsible for antigen recognition, whilst the invariant chains of the CD3 complex (δ, ɛ and γ) and two zeta (ζ) polypeptides couple antigen recognition to downstream signal transduction pathways. TCRζ (CD247) functions as an amplification module in the TCR signalling cascade and is also essential for the assembly and surface expression of the TCR/CD3 complex. Loss of TCRζ expression is common in chronic infectious and inflammatory diseases, as well as in cancer. Previous work has indicated that TCRζlow -expressing cells phenotypically resemble antigen-experienced effector T cells. Here, we describe the derivation of a flow cytometry-based TCRζ expression index for the purpose of more precisely defining TCRζ expression, in addition to utilising a simple transmigration assay in the demonstration that TCRζdim T cells have intrinsic migratory properties that may explain their accumulation at sites of inflammation.