Process for preparing urea-functional organopolysiloxanes made up of units of the formula R n SiO (4-n)/2 where R is a radical R 1 or a radical -OR 2 or a radical Q, R 1 is a monovalent optionally halogenated hydrocarbon radical having from 1 to 18 carbon atoms, R 2 is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, Q is a urea-functional radical of the formula -R 5 -[NR 4 -R 6 -] x NR 4 R 3, where R 3 is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, preferably a hydrogen atom, the radicals R 4 are identical or different and are each a radical R 4 ' or a radical R u, where R 4 ' is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, R u is a radical of the formula -C(=O)-NH 2 R 5 is a divalent C 1 -C 18 -hydrocarbon radical, preferably a divalent C 2 -C 4 -hydrocarbon radical, R 6 is a divalent C 1 -C 18 -hydrocarbon radical, preferably a divalent C 2 -C 4 -hydrocarbon radical, x is 0, 1 or 2 and n is 0, 1, 2 or 3 and preferably on average from 2.00 to 2.66, with the proviso that at least one urea-functional radical Q, which has a radical R u is present per molecule in the organopolysiloxanes made up of units of the formula, by reacting amino-functional organopolysiloxanes made up of units of formula R' n SiO (4-n)/2, where R' is a radical R 1 or a radical -OR 2 or a radical A, R 1, R 2 and n are as defined above and A is an amino-functional radical of the formula -R 5 -[NR 4 '-R 6 -] x NR 4 'R 3, where R 3, R 4 ', R 5, R 6 and x are as defined above, with the proviso that at least one amino-functional radical A is present per molecule in the organopolysiloxanes made up of units of formula, with ortho-substituted aryl carbamates of the formula R 7 -Ar-O-C(=O)-NH 2, where Ar is an ortho-substituted aryl radical, preferably an ortho-substituted phenyl radical, where Ar can contain further substituents in the ortho', meta or para position in addition to the ortho substituent R 7, and R 7 is the ortho substituent bound to Ar, where R 7 is a C 1 -C 6 -alkyl radical, a C 1 -C 6 -carboxalkyl radical, a C 1 -C 6 -alkoxy radical or a halogen radical. R is a radical R 1 or a radical -OR 2 or a radical Q, R 1 is a monovalent optionally halogenated hydrocarbon radical having from 1 to 18 carbon atoms, R 2 is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, Q is a urea-functional radical of the formula R 3 is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, preferably a hydrogen atom, the radicals R 4 are identical or different and are each a radical R 4 ' or a radical R u, where R 4 ' is a hydrogen atom or a monovalent C 1 -C 6 -hydrocarbon radical, R u is a radical of the formula R 5 is a divalent C 1 -C 18 -hydrocarbon radical, preferably a divalent C 2 -C 4 -hydrocarbon radical, R 6 is a divalent C 1 -C 18 -hydrocarbon radical, preferably a divalent C 2 -C 4 -hydrocarbon radical, x is 0, 1 or 2 and n is 0, 1, 2 or 3 and preferably on average from 2.00 to 2.66, R' is a radical R 1 or a radical -OR 2 or a radical A, R 1, R 2 and n are as defined above and A is an amino-functional radical of the formula Ar is an ortho-substituted aryl radical, preferably an ortho-substituted phenyl radical, where Ar can contain further substituents in the ortho', meta or para position in addition to the ortho substituent R 7, and R 7 is the ortho substituent bound to Ar, where R 7 is a C 1 -C 6 -alkyl radical, a C 1 -C 6 -carboxalkyl radical, a C 1 -C 6 -alkoxy radical or a halogen radical.