Insertion of self-expandable metallic stents (SEMS) can provide rapid relief of malignant colorectal obstruction and can be used as a palliative treatment or as a bridge to surgery. A SEMS can be classified as an uncovered or covered stent. Both types of stents have their own merits and demerits. The objectives of this study were to compare success rates, durability, and complication rates of uncovered and covered stent groups of malignant colorectal obstruction. DESIGNS AND SETTING: A nonrandomized prospective, single-center study. We studied 80 patients with malignant colorectal obstruction: colon cancer in 70 patients, metastatic lesion of advanced gastric cancer in 8 patients, and cervix cancer in 2 patients. Insertion of uncovered stents was attempted in 39 patients (before surgery in 20, palliative in 19), and covered stents were used in 41 (before surgery in 23, palliative in 18). The stent was inserted into the obstructive sites for preoperative or palliative purposes by using the through-the-scope method. After stent insertion, the patients had regular follow-ups, either as clinical checkups or telephone interviews. Insertion success rate, durability, and complication rate according to stent type. Technical and clinical success rates of uncovered and covered stents were not different (100%; 95.1%, P > .05, 100%; 97.4%, P > .05). The early stent migration rate was not different in both groups. The late stent migration was more common in the covered stent group than the uncovered stent group (0% vs 40%, respectively, P = .005). Loss of stent function during the long-term follow-up period was more frequent in the covered stent group than in the uncovered stent group (18.8% vs 60%, respectively, P = .018). This was a small-sized, nonrandomized, prospective, single-center study. Confirmation of large-scale, multicenter, randomized, prospective outcome is required. Insertion of either an uncovered or covered stent is similarly an effective treatment modality of malignant colorectal obstruction for preoperative purposes. However, there are no advantages of covered stents over uncovered stents during the follow-up period in the palliative purpose.