The T cell receptor complex, expressed on the surface of T-cells, comprises the antigen-specific heterodimeric αβ T-cell receptor (TCR) that is non-covalently associated with the CD3 complex. Ligation of the TCR by an Antigen (Ag) presenting molecule initiates T-cell signalling.  While is conventionally considered that TCRs interacts with peptide Ags bound to the Major Histocompatibility Complex (MHC), TCRs also interact with lipid-based Ags bound by CD1 family members. Moreover, we have recently established how T-cells can recognise microbial-based vitamin B metabolites.  I shall discuss these recent advances in T-cell biology.