Abstract: A synovial tissue binding peptide comprises an amino acid sequence motif comprising RLP, SPS, HSS, LSS, TWS, YSS, NQR, DRL or DHR. Preferred motifs comprise HPRLPFA, APNWRLP, SPSPFRA, SPSRFDQ, VSPSRTT, PLSSAQR, TWSATST, THSSATQ, HTHSSNL, PNHSSPH, ADHSSRH, SDYSSRS, QTHNQRY, TNQRLAI, KSTHDRL, PFHDRHS, HPSDRLS or DRLNHQE. Also provided is a method for the identification of peptides capable of binding to a tissue originating from a first mammalian species, the method comprising the steps of: grafting the tissue originating from the first mammalian species into a subject of a second mammalian species having an attenuated immunological response; introducing a plurality of peptides into the second species; and determining the localisation of the peptides within the second species.