This paper deals with a study of the ability of a P-glucuronidase from bovine liver to catalyse transglucuronidation reactions. Our results show that when sodium (p-nitrophenyl beta-D-glucopyranosid)uronate was used as a donor and as an acceptor, the sodium (sodium beta-D-glucopyranosyluronate)-(1 --> 3)-(p-nitrophenyl beta-D-glucopyranosid)uronate and the (1 --> 2) regioisomer were obtained in yields of 18 and 15%, respectively. A different regioselectivity was observed using p-nitrophenyl alpha-D-galactopy-ranoside as an acceptor leading to the synthesis of p-nitrophenyl (sodium beta-D-glucopyranosyluronate)-(1 --> 4) alpha-D-galactopyran-oside and of the (1 --> 2) regioisomer in yields of 16 and 21%, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.