Zirconium-desferal was prepared and analysed by TLC, NMR and u.v.-spectroscopy. The stoichiometry of the complex was found to be 1:1. Chelation of desferal, coupled to resin, with 88Zr appeared to be fast and almost quantitative in various buffer systems in a broad pH-range (4-7). A high in vitro stability of the zirconium-desferal complex was observed; less than 0.2% zirconium was lost within 24 h in plasma-solutions.