The present invention relates to the use of gene expression profiles, obtained in vitro from a patient sample, for detecting any postoperative tissue incompatibility reactions following a liver transplantation, wherein in patients the gene activity of a plurality of specific genes relevant to a liver transplantation is determined in a patient sample, and the specific genes and/or gene fragments for monitoring of postoperative states are selected from the group consisting of: SEQ-ID No. 1 to SEQ-ID No. 532, these preferably being subdivided into several clusters.