OBJECTIVES: Endoscopic findings may assist in the clinical diagnosis of ischemic colitis but have not been systematically characterized. We noted that a single linear colonic ulcer could on occasion be found endoscopically after hypotension and proceeded to investigate its relationship to ischemic colitis. METHODS: Twenty-six patients (19 female and seven male, mean age 71 yr) with endoscopic evidence of a single linear ulcer running along the longitudinal axis of the colon (colon single-stripe sign (CSSS) were retrospectively studied. Colitis etiologies were determined in the CSSS patients and in 58 consecutive patients without a stripe forming a colitis comparison group; clinical course and outcome in CSSS patients subsequently were compared with those in 22 patients with circumferentially involved ischemic colitis. RESULTS: The CSSS was ≥5 cm in length in all instances and isolated to a segment of the left colon in 89%. Evidence of a preceding ischemic event was noted significantly more often in the CSSS (62%) patients than in the colitis comparison group (7%) (p < 0.0001). On blinded histopathological examination, 75% of CSSS cases had microscopic evidence of ischemic injury compared with 13% in the colitis comparison group (p < 0.0001). None of the CSSS patients required surgical intervention, whereas six (27%) patients from the circumferential ischemic colitis group underwent exploration (p < 0.05). Nine patients (41%) in the circumferential ischemic colitis group died, whereas there was one death in the CSSS group (4%) (p < 0.05). CONCLUSIONS: Ischemia can manifest endoscopically as the CSSS. This sign seems to characterize milder disease in the clinical spectrum of ischemic colitis.