Background. The placement of self-expandable metallic stents (SEMS) is known to be effective palliative treatment of malignant gastroduodenal obstruction. There are two types of SEMS Á covered and uncovered Á each with its own advantages and disadvantages. This study was conducted to compare between the clinical outcomes of covered and uncovered stents in patients with malignant gastroduodenal obstruction. Patients and methods. The study was conducted prospectively from January 1998 to June 2007 and 154 patients were included. All had symptomatic gastroduodenal obstruction and were not candidates for curative operation. Seventy patients received covered SEMS, while the other 84 received uncovered SEMS. We compared technical and clinical success rates, tumour ingrowth rate, stent migration rate, stent patency time and patient survival in both SEMS groups. Results. The technical and clinical success rates of the covered and uncovered stent groups did not differ. Stent migration was more frequent in the covered stent group than in the uncovered group (17.1% versus 0%; p00.0001). Tumour ingrowth was more frequent in the uncovered stent group than in the covered group (16.6% versus 2.9%; p00.0066). Stent re-intervention rate, stent patency time and patient survival did not differ between groups. Conclusion. Covered and uncovered stent insertions are technically feasible and effective palliative treatment of malignant gastroduodenal obstruction. Covered stents can reduce the risk of tumour ingrowth, whereas uncovered stents are effective in preventing stent migration. However, covered stents did not differ from uncovered stents in regard to other clinical outcomes.