Introduction: Non-invasive, i.e. serum-based multiparametric panels of biomarkers have been proposed for the diagnostic assessment of liver fibrosis. Aims/Methods: (i) Haptoglobin, ALT, GGT, alpha 2-macroglobulin, apolipoprotein A1 and bilirubin in sera of 4 patients with histological proven fibrosis (F1-F4, A1-A3) were determined in 6 different quality-controlled laboratories. Interlaboratory variations of the calculated Fibrotest Score for staging and Actitest Score for grading (both BioPredictive TM ), and their error ratios compared to biopsy results were calculated. (ii) The variability of obtained Fibrotest/Actitest Scores depending on 64 differential combinations of the allowed analyt-specific maximum/minimum permissible values as determined by the external quality control of the German Association of Laboratory Medicine was determined and the frequency distribution of the results calculated.