During infliximab treatment of perianal Crohn's disease (CD), the healing of the skin opening precedes fistula tract healing and this contributes to abscess formation and fistula recurrence. The aims of this study were to evaluate the efficacy of combined treatment with infliximab and setons for complex perianal fistulas in CD and to define the optimal time for seton removal by anal endosonography (AE). Nine consecutive patients with CD were studied. Perianal sepsis was eradicated when necessary and setons were placed before infliximab therapy. Setons were removed after AE evidence of fistulous tracts healing. Patients received a mean of 10+/-2.3 infliximab infusions. At week 6 all patients showed a reduction in mean CD activity index (p<0.005) and perianal disease activity index (p<0.0001). Complete fistula response was achieved in eight of nine patients. In six patients after a mean of 9.2 infusions, infliximab treatment was discontinued. Clinical and AE response persisted at 19.4+/-8.8 months (range 3-28 months) in five of these patients. One patient had fistula recurrence 20 weeks after infliximab discontinuation and responded rapidly to retreatment. At the time of this report, two patients were still on infliximab and in remission after a mean follow-up of 25+/-5 months. Combined therapy with infliximab and setons with AE monitoring of the response showed high efficacy in the management of patients with CD with complex perianal fistulas.