OBJECTIVES: We aimed to characterize the spectrum of liver enzyme test (LET) abnormalities that occur while using methotrexate for inflammatory bowel disease (IBD). METHODS: A retrospective review was undertaken of subjects using methotrexate for IBD at a single center. The clinical and epidemiological parameters, and hepatotoxicity risk factors, were recorded. Subjects were excluded if cumulative methotrexate doses could not be ascertained, if they had a diagnosis of rheumatoid arthritis or psoriasis, or if baseline and follow-up LETs were not available. Also noted were the cumulative methotrexate dose during the peak LET increase, severity of LET increase, and whether normalization occurred. RESULTS: Eighty-seven subjects were included (Crohn's disease, n = 67; UC, n = 17; indeterminate colitis n = 3). The mean therapy duration was 81 weeks (3- to 364-week range), and the cumulative average dose was 1,813 mg (25-8,255-mg range). Thirty-seven (43%) subjects received a cumulative dose >1,500 mg. Sixty-seven (77%) had normal LETs, and in 51 (76%) LETs remained normal throughout methotrexate therapy. In the 16 (24%) who developed LET abnormalities, seven (44%) had underlying risk factor(s) for liver disease. Normalization (without dose reduction) occurred in 14 (88%) while continuing methotrexate. Of 20 subjects with abnormal LETs at baseline, nine (45%) subsequently normalized while continuing methotrexate, whereas nine (45%) worsened. Seventeen liver biopsies were performed in 11 and were classified as Roenigk's grade I in 15 (88%) subjects. Roenigk IIIb or IV was not seen. CONCLUSIONS: Methotrexate is commonly associated with LET abnormalities, but these frequently normalize while still on therapy, and in only 5% will drug discontinuation be necessary. Liver biopsies rarely have substantive abnormalities.