The aim of this study was to investigate the influence of the taurine content in canned diets on plasma taurine concentration. Furthermore the plasma content of bile acids, bilirubin, triglycerides, cholesterine, potassium as well as the activity of alkaline transferase and aspartate amino transferase were examined. For this cross over study eighteen cats were allocated into two groups of nine cats each. The age of the cats was about ten years. From day 1 to day 56 group 1 was fed an experimental diet containing 862 mg taurine/kg dry matter (DM) and group 2 was given the commercial canned food containing 1,930 mg taurine/kg DM. During the following 56 days group 1 was given the commercial diet and group 2 received the experimental taurine-poor diet. Blood samples were taken at the beginning, after 28, 56, 84 and 112 days. The mean plasma taurine content decreased from 133 +/- 53.6 mu mol/l to 29.4 +/- 14.6 mu mol/l in group 1 and from 89.2 +/- 54.4 mu mol/l to 15.9 +/- 7.1 mu mol/l in group 2 when the taurine reduced diet was given. The plasma taurine concentration and the concentration of bile acids were positively correlated (r(s) = 0.29, n = 68; Pearson Korrelation). During feeding the taurine poor diet, the concentration of serum bile acids decreased from 25.4 +/- 14.4 mu mol/l to 8.4 +/- 4.9 mu mol/l in group 1 and from 28.1 +/- 12.7 mu mol/l to 18.8 +/- 6.7 mu mol/l in group 2. There was a negative correlation (r(s) = -0.29, n = 72) between the activity of the alkaline phosphatase and the plasma taurine concentration. No correlation was determined between the content of bilirubin or potassium and the taurine concentration.