Abstract Introduction The use of the drug infliximab for the treatment of patients with Crohn's disease can be complicated by tuberculosis. A paradoxical reaction during antituberculosis chemotherapy and immunologic reconstitution after discontinuation of infliximab can result in severe disseminated tuberculosis. Case presentation A 38-year-old Korean man with severe Crohn's disease presented with fever and diffuse abdominal pain. Infliximab had been started 2 months before admission. A chest X-ray and abdominal computed tomography scan revealed numerous miliary nodules in both lung fields and microabscesses in the spleen. Given the diagnosis of disseminated tuberculosis, the infliximab therapy was discontinued and antituberculosis therapy was promptly started. Over the next 3 months, the patient was diagnosed with tuberculosis lymphadenitis on a right supraclavicular lymph node and surgical excision of the lesion was performed. With the diagnosis of a paradoxical response, anti-tuberculous therapy was continued for 12 months. Conclusion Our case suggests that patients who develop tuberculosis after infliximab exposure are at an increased risk of developing a paradoxical reaction. The current recommendation of discontinuing infliximab during tuberculosis treatment should be re-evaluated.