Objective To assess surgical outcomes between the non-renorrhaphy and renorrhaphy techniques in open partial nephrectomy for ≥T1b renal tumors using volumetric studies. Methods We retrospectively analyzed the records of 91 patients with normal contralateral kidneys who underwent both open partial nephrectomy for ≥T1b renal tumors and pre- and postoperative enhanced computed tomography between 2010 and 2014. Volumetric studies to assess vascularized parenchymal volume of the operated kidney were performed within 2 months preoperatively and 6 months postoperatively. Using the non-renorrhaphy technique, we coagulated hemorrhagic areas on the surface of the renal parenchyma by monopolar soft coagulation, while a TachoSil tissue-sealing sheet was placed on the resected bed. Results A total of 50 patients underwent renorrhaphy and 41 patients underwent non-renorrhaphy. Patient backgrounds and R.E.N.A.L. nephrometry scores were not significantly different between the two groups. Cold ischemia time was significantly longer in the renorrhaphy than that in the non-renorrhaphy (52 vs 42 minutes, P  = .0162). However, significant differences were not observed in the preservation rate of the vascularized parenchymal mass in the operated kidney (renorrhaphy, 71%; non-renorrhaphy, 70%; P  = .5054) and global kidney function (renorrhaphy, 88%; non-renorrhaphy, 90%; P  = .3653) between the two groups. Renal artery pseudoaneurysm occurred in 2 cases in both groups. Urinary fistula tended to occur more frequently in non-renorrhaphy (2 cases) than in renorrhaphy (5 cases), though this difference was not statistically significant ( P  = .237). Conclusion The non-renorrhaphy technique failed to show a benefit in the preservation of vascularized parenchymal mass of the operated kidney and global renal function for ≥T1b renal tumors compared to the renorrhaphy technique.