AIMS: To assess fistula track healing after infliximab treatment using magnetic resonance imaging. METHODS: Magnetic resonance imaging and clinical evaluation were performed before and after three infliximab infusions given over a 6-week period. Magnetic resonance images were evaluated for abscesses and fistula tracks. Paired magnetic resonance image examinations were rated 'better', 'unchanged' or 'worse'. Magnetic resonance imaging and clinical outcomes were then compared. RESULTS: Of the 12 referred patients, pre-treatment magnetic resonance imaging detected abscesses in three (two not treated). Of the 10 treated patients, seven had peri-anal fistulas, two of whom also had recto-vaginal fistulas, and three had abdominal wall entero-cutaneous fistulas. After infliximab, four were in remission, one had a response and five were non-responders. One developed a peri-anal abscess. Magnetic resonance imaging improved in six, was unchanged in two and was worse in two. In four of the six with improvement in magnetic resonance imaging, the fistula track resolved, but two of these had clinically persistent entero-cutaneous fistulas. The clinical outcome and magnetic resonance imaging correlated in seven of the 10 patients; in three (two entero-cutaneous and one peri-anal), there was discordance. CONCLUSIONS: Magnetic resonance imaging identifies clinically silent sepsis. Fistulas may persist despite clinical remission. Clinical response to infliximab and clinical correlation with magnetic resonance imaging were poor in patients with abdominal entero-cutaneous fistulas.