Adenosine is a powerful direct coronary vasodilator with a very short half-life that has been shown to be effective in avoiding and reversing no reflow. We report an immediate successful recanalization of an occluded major side branch after stenting with acute intracoronary adenosine administration. The beneficial effect of adenosine may imply that the side branch occlusion (SBO) in this case could be due to spasm or distal embolization of the atherosclerotic debris ending up with no flow. We believe that adenosine could be helpful in at least some cases of SBO and therefore may be worth attempting.