Abstract The clinical presentation of acute onset of nausea, vomiting, and flank pain in combination with acute elevation of blood pressure should raise high suspicion of renal infarction. However, because of its nonspecific presentation, diagnosis may be delayed. We report the case of a 63-year-old man who presented with a 2-day history of right flank pain that was treated initially as a renal stone. He had a background history of atrial fibrillation. Further investigations confirmed this as a case of renal infarction. Renal infarction is underdiagnosed because of the similarity of its presentation to other renal pathology. Renal infarction should be considered in the differential diagnosis of loin pain, particularly in a patient with atrial fibrillation.