New di- and triorganotin(IV) derivatives of tyrosinylphenylalanine (H 2 Tyr-Phe) with general formulae R 2 Sn(Tyr-Phe) where R=Me,n-Bu, n-Oct and Ph, and R 3 ′ Sn(HTyr-Phe) where R ′ =Me and Ph have been synthesized. The bonding and coordination behaviour in these derivatives are discussed on the basis of FT-IR, multinuclear 1 H, 13 C and 119 Sn NMR and 119 Sn Mössbauer spectroscopic studies. These investigations suggest that dipeptide in R 2 Sn(Tyr-Phe) acts as dianionic tridentate coordinating through −C(O)O − , –NH 2 and (–CO)N − peptide groups while in case of R ′ 3 Sn(HTyr-Phe) the ligand acts as monoanionic bidentate coordinating through –C(O)O − and –NH 2 , and the polyhedron around tin in R 2 Sn(Tyr-Phe) and R ′ 3 Sn(HTyr-Phe) is a distorted trigonal-bipyramidal. It is further confirmed by the single crystal X-ray structure of Me 2 Sn(Tyr-Phe)·MeOH which shows two methyl groups and peptide nitrogen (N − peptide ) in the equatorial positions, while the two axial positions are occupied by the carboxylic oxygen (O − carboxyl ) and the amino nitrogen (N amino ) atom from the same ligand molecule. One methanol molecule is also present in the asymmetric unit.