Left main dissection (LMD) is a rare but feared complication of cardiac catheterization. It is usually managed by bailout stent implantation or coronary artery bypass surgery. We describe a case of iatrogenic, retrograde LMD during percutaneous coronary intervention. After covering the retrograde entry of the dissection in the ostial left anterior descending artery (LAD), optical coherence tomography (OCT) showed, that there was no antegrade entry in the left main and that the minimal true lumen area in the left main was 7.2 mm2. It was therefore decided to treat the LMD conservatively and reassess the results by angiography 6 months later. At follow-up angiography, no stenosis or residual dissection in the left main were noted. The patient was doing fine at 1-year follow-up. OCT is a valuable tool for assessing coronary artery dissections and may guide the decision, whether to stent or not to stent a dissection. In selected cases LMD may be managed conservatively. © 2013 Wiley Periodicals, Inc.