Renal biopsy is the gold standard diagnostic method in adults with the renal parenchymal disease. Retroperitoneal hemorrhage is one of the rare and most severe complications of percutaneous renal biopsy. The incidence of hemorrhagic complications due to interventional procedures in patients with enoxaparin use is 1.9-6.5%. Patients undergoing percutaneous renal biopsy under anti-coagulant therapy should be carefully monitored for this potentially fatal complication after a biopsy. In this case report, we presented a 45-year-old female patient who was admitted to our nephrology department for renal biopsy for unexplained proteinuria and hematuria. Because of mitral valve replacement history, a percutaneous renal biopsy was performed under low molecular weight heparin treatment. The follow-up and treatment process of retroperitoneal hemorrhage after the procedure were described.