During PN, the surgeon's understanding of the relevant intrarenal anatomy is currently based on a 3-D understanding of preoperative CT images, combined with intraoperative endoscopic visualization and ultrasound. Based on thin-slice CT, we developed a novel 3-D reconstruction technique that fuses key anatomical aspects: 1 surface-rendered renal tumor, semi-transparent kidney, extra-and intrarenal arterial anatomy (especially focused on tumor-feeding artery), and urinary collecting system. Based on the developed concept of a 3-D reconstructed model for PN, various surgical navigation or simulation techniques have been reported, including the use of TilePro display, movable tablet display or a 3-D printed model. [2][3][4] Although a 3-D printed model was reported to facilitate patient education or understanding of surgery, an important unresolved issue remains regarding the possible role to enhance the surgeon's real surgical skill or to assist the surgeon in determining the optimal approach. 4 Pre-and intraoperatively, it would be a vital surgical simulation if you could see the cancer and its feeding artery as a magnified view on the intended surgical incision-line, as if you were getting smaller to the millimeter level inside the surgical field. VR is a digitalized computer-generated experience of the simulated field, and might allow us this opportunity, with head-mounted VR headsets or a multiprojected environment. 5 The evolving information technology could provide a new opportunity to enable surgeons to participate in a VR-based 3-D surgical field, which potentially enhances the surgeon's experience or assists in the surgeon's decision-making for finding an optimal approach. Herein, our initial experience of VR with head-mounted headsets is reported as a proof-of-concept to potentially assist in surgical planning and intraoperative management.In the present study, first, a 3-D renovascular tumor model was reconstructed in a case involving a renal tumor (diameter 2.2 cm) on the right kidney from thin-slice CT (Fig. 1a). We processed the patient's DICOM images by outlining the tumor, intra-and extra-renal arteries, urinary collecting system, and renal parenchyma. Subsequently, the DICOM data were converted into STL files using the medical image analysis application OsiriX (Pixmeo S arl, Bernex, Switzerland). The STL files were uploaded to the Holoeyes website (https:// holoeyes.jp/en/; Holoeyes, Tokyo, Japan). The 3-D images had been automatically converted into a case-specific VR simulation, which could be viewed through the head-mounted headset of Mirage Solo (Lenovo, Hong Kong). The surgeon wearing the Mirage Solo could see the VR-based surgical anatomy as a magnified view, as if getting smaller to the millimeter level inside the surgical field (Fig. 1b,c). It is also possible to change the surgeon's viewpoint, so that they can see not only inside the organ, but also view the surgical field from outside on various angles. Thus, the Mirage Solo provides a new opportunity to understand the spatial relationship...