Mineralization and degradation of 14C-ring-labelled isoproturon were investigated over 120 days under controlled laboratory conditions in three soils of eastern France chosen for their pH : a pelosol, a brown calcareous soil and a brown acid soil. Biological activity of the micro-flora was also measured by release of total CO2. Common metabolites of isoproturon found in the three soils were N-(4-isopropyl phenyl)-N'methylurea and N-(4-(2-hydroxyisopropylphenyl))-N'methylurea. Moreover N-(4-isopropylphenyl)urea was also found in brown acid soil. Other residues were detected ; one in the pelosol and two in the brown acid soil. Analysis of non identified product of pelosol only revealed a polar affinity by presence of hydroxy fonction. One of the residues found in brown acid soil was characterised by GC/MS as 4,4'-diisopropylazobenzene.