Anti-TNF monoclonal antibodies are a cornerstone in the treatment of Crohn's disease. Prospective data on switching from the subcutaneous and human adalimumab (ADM) to the intravenous and chimeric infliximab (IFX) are scarce. In this prospective, observational, multicentre cohort study we included 21 patients with loss of response to ADM despite at least 4 consecutive weekly injections. Clinical response (CDAI drop≥70 points) and remission (CDAI≤150) were assessed after switching from ADM to IFX after 10 weeks, 6 and 12 months. Predictive factors of response/remission, the need for therapy intensification, discontinuation and safety were investigated. Short-term response and remission (10 weeks) were seen in 57% and 48% respectively. Mid- and long-term clinical response and remission were achieved in 40% and 25% after 6 months and in 45% and 20% after 12 months respectively. At 12 months, 81% still were on IFX. IFX therapy intensification was needed in half of the patients at 6 months and three quarter of patients at 12 months. Undetectable ADM trough levels (despite weekly injections) were a predictive factor for short-term response and remission to IFX. About half of the patients with response at week 10 maintained response at 6 and 12 months. Switching from ADM to IFX can be efficacious in patients with loss of response, in particular in case of undetectable ADM trough levels. The majority of patients however will need IFX therapy intensification during their first year of treatment.