In this case report, we examined the levels of cytokines expressed before and during fecal stream diversion and after intestinal continuity was restored in a patient with collagenous colitis. We report the case of a46-year-old woman with chronic, active collagenous colitis who either failed to achieve clinical remission or experienced adverse effects with the following drugs:loperamide, cholestyramine, budesonide, methotrexate and adalimumab. Due to the intractable nature of the disease and because the patient was having up to 15 watery bowel movements per day, she underwent a temporary ileostomy. Colonic biopsies were analyzed for mucosal cytokine protein levels before and during fecal stream diversion and after intestinal continuity was restored. Mucosal protein levels of interleukin(IL)-1β,IL-2, IL-6, IL-12, IL-17 A, IL-23, TNF, IFN-γ, IL-4, IL-5,IL-10 and IL-13 were all higher during active disease and decreased to non-detectable or considerably lower levels during fecal stream diversion. One month after the restoration of bowel continuity, when the patient experienced a relapse of symptoms, IL-2, IL-23 and IL-21 levels were again increased. Our results indicate that fecal stream diversion in this patient suppressed the levels of all cytokines analyzed in colonic biopsies. With the recurrence of clinical symptoms and histological changes after bowel reconstruction,the levels of primarily proinflammatory cytokines increased. Our findings support the hypothesis that a luminal factor triggers the inflammation observed in collagenous colitis. In this case report, we examined the levels of cytokines rendered before and during fecal stream diversion and after intestinal continuity was restored in a patient with collagenous colitis. We report the case of a46-year-old woman with chronic, active collagenous colitis who either failed to achieve clinical remission or experienced adverse effects with the following drugs: loperamide, cholestyramine, budesonide, methotrexate and adalimumab. Due to the intractable nature of the disease and because the patient was having up to 15 watery bowel movements per day, she underwent a temporary ileostomy. Colonic biopsies were analyzed for mucosal cytokine protein levels before and during fecal stream diversion and after intestinal continuity was restored. Mucosal protein levels of interleukin (IL) -1β, IL-2, IL-6, IL- 12, IL- 17 A, IL-23, TNF, IFN-γ, IL-4, IL-5, IL-10 and IL-13 were all higher during active disease and decreased to non-detectable or considerably lower levels during fecal stream d One month after the restoration of bowel continuity, when the patient experienced a relapse of symptoms, IL-2, IL-23 and IL-21 levels were again increased. Our results indicate that fecal stream diversion in this patient suppressed the levels of With the recurrence of clinical symptoms and histological changes after bowel reconstruction, the levels of primarily proinflammatory cytokines increased. Our findings support the hypothesis that a luminal factor triggers the inflammation observed in collagenous colitis.