Objective: Large solitary renal cysts (SRC) may result in renal ischemia. Renalase, a protective enzyme against ischemic renal injury, has an effective role in controlling blood pressure (BP). Therefore, we aimed to investigate the relationships among pre- and postoperative serum angiotensinogen, epinephrine, renalase/epinephrine ratio, and BP in patients who underwent laparoscopic cyst decortication.Materials and Methods: We included 20 patients with large SRC and 16 healthy individuals in this prospective study. Cysts were diagnosed by ultrasonography and characterized using computed tomography. Blood and urine samples were collected during pre- and postoperative periods. In addition, 12-hour ambulatory BP values were recorded. Serum angiotensinogen, renalase, and epinephrine levels were measured by the enzyme-linked immunosorbent assay method.Results: There was no statistically significant difference in angiotensinogen and renalase levels between patient and control groups (p=0.205, p=0.163, respectively), but preoperative renalase/epinephrine ratio was significantly higher in patients (p=0.006) than in the control group. In addition, renalase/epinephrine ratio was significantly lower in the postoperative period (p=0.018). Univariate and multivariate logistic regression analyses demonstrated that a higher renalase/epinephrine ratio was associated with the presence of SRC (p=0.028, p=0.016, respectively).Conclusion: A high renalase/epinephrine ratio may be associated with the presence of large SRC. We think that renalase may be a biomarker in the management of SRC and decision making in surgical procedures. Association of renalase with large SRC should be explored in future studies.