BACKGROUND: Methotrexate can be used to maintain remission in Crohn's disease patients who are intolerant to thiopurines. Data on its use as monotherapy in other scenarios are limited. AIM: To assess the effectiveness of methotrexate monotherapy in Crohn's disease patients after previous failure to anti-tumour necrosis factor (anti-TNFalpha) drugs. METHODS: A retrospective, observational multicentre study of data from the Spanish ENEIDA registry. Participants were patients with active Crohn's disease and previous failure to anti-TNFalpha started on methotrexate monotherapy. Short-term effectiveness was assessed at 12-16 weeks based on Harvey-Bradshaw index (HBI): clinical remission as HBI </= 3 points and clinical response as HBI drop of >/= 3 points over baseline. Long-term effectiveness was defined as steroid-free methotrexate persistence from 12 to 16 weeks until maximum follow up. Adverse events were recorded. RESULTS: Data were compiled for 110 patients treated with methotrexate after a failed response to one (39%) or two (55.6%) anti-TNFalpha agents. Short-term clinical response and remission rates were 60% and 30.9% respectively. Of 74 patients who continued after week 16, long-term effectiveness was achieved in 82% and 74% at 12 and 24 months respectively. In the multivariate analysis, non-remission at short term (vs remission) was associated with long-term failure (HR 2.58, 95%CI 1.95-3.68, P = 0.028). Adverse events (evaluated in 100 patients) were recorded in 44%, and in 30.4% of these patients, they led to methotrexate discontinuation. CONCLUSIONS: The benefits observed suggest methotrexate monotherapy could be a valid option in Crohn's disease patients with previous failure to anti-TNFalpha.