Objectives: To determine the extent that laparoscopy has replaced open surgery for nephron-sparing surgery in a mature laparoscopic environment. Methods: The records of all patients at Washington University who underwent nephron-sparing surgery for localized renal masses from 1999 to 2003 were examined for clinical and pathologic information. Information regarding the mass size, surgery type performed, and surgeon training was obtained. Results: A total of 271 patients underwent nephron-sparing surgery from January 1999 to December 2003. During the study period, the total number of partial nephrectomies increased from 33 per year to 91 per year. The proportion of laparoscopic partial nephrectomy increased from 3% of total cases to 56% of total cases. Open partial nephrectomy decreased from 97% of cases to 24% of cases; however, the absolute number of open partial nephrectomies only decreased from 32 to 22 per year. Laparoscopic cryoablation increased from 0% of cases to 20% of cases. Endourologists increased their frequency of performing open partial nephrectomy, and oncologists increased their frequency of performing laparoscopic renal surgery. Conclusions: Laparoscopic nephron-sparing surgery has not completely replaced open partial nephrectomy for low-stage renal neoplasia; however, the number of laparoscopic partial nephrectomies has increased rapidly in recent years. Laparoscopic approaches are being performed by all urologists treating renal malignancies at our institution and this reflects changes in the surgical treatment of renal cancer.