The present invention relates to methods for identifying and/or classifying patients with inflammatory bowel diseases (IBD), particularly patients with Crohns disease or ulcerative colitis. Gene expression profiling shows broad and fundamental differences in the pathogenic mechanism of UC and CD. The subject method is based on the findings that certain genes are differentially expressed in intestinal tissue of IBD patients compared with related normal cells, such as normal colon cells. That change can be used to identify or classify IBD cells by the upregulation and/or downregulation of expression of particular genes, alterations in protein levels or modification, or changes at the genomic level (such as mutation, methylation, etc), e.g., an event which is implicated in the pathology of inflammatory bowel diseases.