Portacaval transposition was performed in ten dogs, followed by hemodynamic, biochemical, and histologic studies at intervals up to 12 weeks. All survivors appeared to be in excellent condition clinically at the time of study. Six to 12 weeks following transposition, total hepatic blood flow was in the high normal or slightly elevated range, with a significant (50%) increase in venous flow component from the caval source and a significant (32%) reduction in hepatic artery component. Despite the high normal or slightly elevated total hepatic blood flow and excellent clinical condition, all animals studied after six weeks showed slight biochemical and histopathological evidence of liver damage. Postoperative course and clinical condition of dogs with portacaval transposition, compared to dogs with conventional portacaval shunts, is very encouraging when considering application of this procedure for portal decompression.