Renal infarction is a rare disease in clinical practice, in most cases it is triggered by predisposing thromboembolic factors, with atrial fibrillation being the main risk factor, only a minority of cases is associated with small vessel vasculitis and another large percentage is idiopathic. Semiologically it presents with severe, sudden low back pain that simulates renoureteral colic; this clinical presentation obliges to rule out urolithiasis, so the diagnosis is usually late and exclusion. The study of diagnostic choice is the computed axial tomography of the contrasted abdomen. The basis of treatment is anticoagulation, mainly with coumarins. A patient is presented, without risk factors, previously healthy, who debuted with sudden intense left lumbar pain, the diagnosis was made with contrasted abdominal tomography and it was determined that the etiology of the renal infarction was finally idiopathic after ruling out atrial fibrillation, thrombophilia and vasculitis More studies are needed to provide guidelines in the treatment of this idiopathic percentage of patients.