The GuideLiner catheter is an easy-to-use guide catheter extension that can facilitate vessel engagement and equipment delivery. We present two cases that illustrate two potential challenges associated with use of the GuideLiner catheter: (1) stent loss and deformation during attempts to advance it through the GuideLiner catheter collar; and (2) displacement of the GuideLiner catheter distal marker into a coronary artery. Awareness of these potential complications may render safer the use of this valuable interventional tool.