Objective: To report our experience in treating endophytic renal tumor by robot-assisted partial nephrectomy (RPN) with a standard laparoscopic ultrasound probe and our original approach for separating renal mass. Methods: All patients with endophytic renal tumor who underwent RPN in our department from January 2015 to December 2017 were retrospectively analyzed. All surgeries were performed by transperitoneally by a single, experienced surgeon. Baseline characteristics, tumor characteristics, operative profile and follow-up data were collected. Results: Among these 29 patients, 23 patients were male. The mean age of patients was 47.42 years old. 69% (20/29) tumors were completely endophytic tumors. The average tumor size was 3.1 cm. The average R.E.N.A.L. score was 9.0. Tumors from 3 patients were pathologically confirmed to be renal angiomyolipomas. And the rest were malignant including 23 clear cell renal cell carcinoma and 3 chromophobe renal cell carcinoma. The mean operative time was 3.0 h. The mean warm ischemia time was 22.3 min. All tumor margins were pathologically confirmed negative. No patient needed blood transfusion. Two patients presented had Grade II complication. Both of them had a fever after surgery with body temperature over 38 degrees C, leading to a prolonged postoperative hospitalization time. The mean postoperative hospitalization time was 6.8 days. During mean 21.3-month follow-up, no patient was confirmed to relapse by CT scan. Conclusion: RPN with a standard laparoscopic ultrasound probe is safe, effective and feasible in treating endophytic renal tumor. Our original approach for separating renal mass can avoid some problems caused by the standard laparoscopic ultrasound probe. (C) 2019 Asian Surgical Association and Taiwan Robotic Surgery Association. Publishing services by Elsevier B.V.