The tripeptide NH₂-Gly-His-Lys-COOH (GHK), <i>cis</i>-urocanic acid (<i>cis</i>-UCA) and Cu(II) ions are physiological constituents of the human body and they co-occur (e.g., in the skin and the plasma). While GHK is known as Cu(II)-binding molecule, we found that urocanic acid also coordinates Cu(II) ions. Furthermore, both ligands create ternary Cu(II) complex being probably physiologically functional species. Regarding the natural concentrations of the studied molecules in some human tissues, together with the affinities reported here, we conclude that the ternary complex [GHK][Cu(II)][<i>cis</i>-urocanic acid] may be partly responsible for biological effects of GHK and urocanic acid described in the literature.