OBJECTIVE Isolated superior mesenteric arterial dissection (ISMAD) is an uncommon type of arterial dissection and treated with surgery, stenting, or conservative management. This study aimed to evaluate the criteria for conservative therapy for ISMAD patients based on imaging findings. METHODS Eighteen consecutive ISMAD patients without peritoneal irritation at onset were retrospectively studied. The decision to perform stenting was based on the emergence of peritoneal irritation, aneurysm, or mesenteric ischemia. Clinical manifestations, follow-up contrast-enhanced computed tomography (CECT) findings, and patient outcome were evaluated. RESULTS Most patients (16, 89%) were successfully treated conservatively; two patients (11%) required endovascular stenting because of an aneurysm or ulcer-like projection (ULP) sign. The median duration of fasting and hospital stays was 3 (range, 1-8) and 9 (range, 4-34) days, respectively. On CECT, the median distance from the superior mesenteric artery (SMA) origin to the entry site was 12 mm (range, 5-35 mm), and the median length of dissection was 87.5 mm (range, 20-150 mm). Among 16 patients treated conservatively, serial imaging was obtained in 11 patients (69%), and disappearance of the dissection within 4 months occurred in five patients. Two patients treated with endovascular stent underwent follow-up CECT 1 year after onset, and there were no complications. CONCLUSIONS ISMAD patients without peritoneal irritation can be treated conservatively if there are no signs of an aneurysm, ULP, or mesenteric ischemia. When an aneurysm or ULP sign exists, endovascular stenting was able to preserve SMA blood flow with the improvement of the dissection.