The present invention relates to a peptide which is immunologically recognizable as a T cell epitope of the minor Histocompatibility antigen H-Y. The peptide comprises amino acid sequence SPSVDKARAEL (SEQ ID NO: 1) or FIDSYICQV (SEQ ID NO: 2). The peptide is obtainable from the minor Histocompatibility antigen H-Y. Providing a toxic moiety to the peptide eliminates T cells having specific binding affinity for the peptide. The peptide induces tolerance for transplantations when administered to H-Y-negative recipients.