Abstract: The present invention relates to methods and kits for diagnosing ulcerative colitis in a subject. In particular, the present invention relates to a method for diagnosing ulcerative colitis in a subject comprising the steps consisting of determining in a sample obtained from the subject the expression level of at least one gene selected from the group consisting of ADH4, ADH6, ADHFE1, AKR1A1, AKR7A2, ALDH1A3, ALDH1L1, ALDH7A1, AOX1, BCHE, CBR3, CES1, CYP1B1, CYP2E1, CYP2W1, CYP4F11, CYP51A1, ESD, KCNAB2, COMT, GSTA4, GSTP1, INMT, MGST2, SULT2A1, TPMT, UGT1A4, UGT1A9, UGT2B7, ABCA1, ABCA2, ABCB1, ABCC1, ABCC10, ABCC5, ABCC6, ABCG2, ATP7A, SLC1A3, SLC7A5, SLC10A2, SLC15A1, SLC15A2, SLC19A2, SLC19A3, SLC22A3, SLC28A3, SLC29A2, SLC38A1, SLC38A5, SLC47A1, SLCO2B1, SLCO4C1, ARNT, FOXO1, HIF3A, NCOA2, NCOR2, NR1H3, NR3C1, PPARD, PPARGC1A, RARB, RXRB, and THRB.