Idiopathic mesenteric phlebosclerotic colitis (IMP) is a rare disease entity of intestinal ischemia that is predominant in Asian populations. We present the clinical features, diagnosis, treatment, and outcome of this disease via a case series. We collected data from medical records in two medical centers in Taiwan. From 2008 to 2017, 11 cases were diagnosed with IMP, and their clinical features were analyzed. Eleven cases were included in our case series. The average age of the patients was 59 (±6.77) years old, and there was a predominance of women. More than half of our patients had a history of herb consumption. Their symptoms varied from asymptomatic to lethal, such as mechanical ileus. The most common colonoscopic finding was the dark purple discoloration and decreased vascularity over the edematous mucosa. In our case series, nine patients showed no disease progression after conservative treatment alone. In contrast, two cases required surgical intervention due to mechanical ileus. The symptoms of IMP may vary extremely, and it may present as asymptomatic or lethal. The etiology of this rare disease remained unknown, and some offending materials such as herb were considered responsible for its genesis. Both the specific radiological and colonoscopic characteristics helped to confirm its diagnosis. IMP should be always considered for ischemic colitis in long-term herb users.