Recent studies have shown a low adherence rate to maintenance treatment in patients with inflammatory bowel disease (IBD). We sought to assess the medication-taking behavior in a cohort of patients with IBD. We prospectively included IBD patients from the outpatient clinic who agreed to answer a questionnaire about prescribed treatment and adherence. Physicians registered clinical data including prescribed medications. Two hundred fourteen patients (115 Crohn's disease/99 ulcerative colitis) were included. The most prescribed medications were oral mesalazine (56.5%) and immunomodulators (41.1%). Forty-three percent of patients admitted to occasionally forgetting to take their medication but only 7.5% of them did it voluntary. Oral mesalazine and azathioprine were the drugs with the poorest compliance, with nonadherence rates of 45% and 25% of the total prescribed doses, respectively. The only factor associated with a better adherence was a more complicated course of the disease-steroid dependency, steroid refractoriness, need for infliximab treatment, hospitalization, or surgery (P=.02). Twenty percent of patients admitted to self-medicating. An important proportion of patients with IBD admit to forget some doses of the prescribed medication in the setting of a specialized unit of a referral centre.