Angiographic evidence of impaired tissue perfusion, known as the “no-reflow” phenomenon, is a serious complication of percutaneous coronary intervention—one that is associated with increased mortality rates. Adenosine is an endogenous nucleoside that attenuates many of the mechanisms that are responsible for no-reflow. Herein, we report the cases of 4 patients who developed the no-reflow phenomenon after elective percutaneous coronary intervention to their native coronary arteries and saphenous vein grafts. In all 4 patients, and without adverse effects, small bolus doses of adenosine through the guiding catheter improved epicardial perfusion—measured by either Thrombolysis In Myocardial Infarction (TIMI) flow grade or corrected TIMI frame count—and tissue-level perfusion, graded according to myocardial blush. In view of adenosine's extremely short half-life in blood, the continuous administration of adenosine into the distal vascular bed throughout percutaneous coronary intervention may further improve outcomes by reversing or preventing the no-reflow phenomenon.