Objectives: This study aimed to evaluate the characteristics and the feasibility of 18-mm-diameter stents for obstructive colorectal cancer, comparing the clinical courses with 22- mm-diameter stents. Methods: We retrospectively compared 33 consecutive cases treated with 18-mm-diameter stents (bridge to surgery [BTS] in 25, palliative therapy [PAL] in 8) with 27 consecutive cases treated with 22-mm-diameter stents (BTS in 21, PAL in 6) for obstructive colorectal cancer between May 2013 and November 2015 in our institution. Results: There were no significant differences between the 18-mm and 22-mm groups in technical success rates (97 and 96%, respectively) and clinical success rates (100 and 100%, respectively). As a BTS, the rates of complications and stoma formation were not significantly different between groups. For PAL, although the rates of complications and stent patency were similar, stent occlusion occurred in 1 patient (12.5%) in the 18-mm group. Conclusions: The 18-mm-diameter stents were similarly effective when compared with 22-mm-diameter stents. Because 18-mm-diameter stents are easy to handle and produce less mechanical stress, they have the potential to decrease the perforation rate and mitigate the stent's impact on the tumors. 18-mm-diameter stents can be useful and safe, especially as a BTS.