Guidewire insertion into the side branches during percutaneous coronary intervention may be difficult, depending on the angle of the side branch and plaque localization. The reverse wire technique (RWT) is an effective wiring method for markedly angulated bifurcated side branches. Nonetheless, continuing the procedure may be difficult if the RWT system cannot be inserted because of severe main trunk stenosis or if the insertion of the system causes a decrease in the peripheral blood flow. In these cases, balloon pre-dilation is sometimes performed; however, this is unreliable due to the risk of side branch occlusion caused by plaque shift. By performing excimer laser coronary angioplasty (ELCA) as a preparatory procedure before RWT, it is possible to eliminate the main trunk plaque without inducing insufficiency in the side branches. We herein report three acute coronary syndrome (ACS) cases in which ELCA pretreatment was effective after failure of an attempted RWT. This method is considered a novel use of ELCA in ACS.