Degradation of cyprodinil in soil mainly occurs by biological process. Degradation involves hydroxylation of the phenyl or the pyrimidyl ring of cyprodinil to give major CGA 275535 (meta-phenol derivative, max. 20 % after 14 d) and minor (detected in traces) CGA 304075 (para-phenol derivative) and CGA 304076 (hydroxy-pyrimidyl derivative), and cleavage of the anilino- pyrimidyl bridge of cyprodinil and its hydroxy-phenyl derivatives to give major CGA 249287 (amino-pyrimidine, max. 6.5 - 14.3 % after 30 - 363 d) and then minor CGA 321915 (hydroxy-pyrimidine, < 5.1 %). A dimer of CGA 321915 and phenol have been also detected in traces. The phenyl ring and the pyrimidyl ring are poorly mineralized : 5.6 - 14.2 % after 91/92 d and 0.3 - 10.8 % after 90/112 d, respectively. The corresponding figures for bound residues are 36.8 - 61.2 % and 10.6 - 68.3 %. Splitting unextractable RA into humic substances releases only small amounts of cyprodinil and of its main metabolites. A published plant uptake study confirms the low bioavailability of bound residues of cyprodinil. Further analysis of bound residue involving silylation, SEC and 13C-NMR spectroscopy suggest cleavage of cyprodinil molecules before covalent binding of cyprodinil residues to humic acids whereas sequestration in humin of either unchanged or slightly modified molecules of cyprodinil at high dose or cleavage products at normal dose could be a significant process.