BACKGROUND:Because there is limited population-based evidence supporting the comparative effectiveness of laparoscopic radical nephrectomy (LRN) after its widespread adoption, we compared trends in hospital-based outcomes among patients with kidney cancer treated with LRN or open radical nephrectomy (ORN). METHODS: Using linked SEER-Medicare data, the authors identified patients with kidney cancer who were treated with LRN or ORN from 2000 through 2005. The authors measured 4 primary outcomes: intensive care unit (ICU) admission, prolonged length of stay, 30-day hospital readmission, and in-hospital mortality. The authors then estimated the association between surgical approach and each outcome, adjusting for patient demographics, tumor characteristics, and year of surgery. RESULTS: The authors identified 2108 (26%) and 5895 (74%) patients treated with LRN and ORN, respectively. Patients treated with LRN were more likely to be white, female, of higher socioeconomic position, and to have tumor sizes of 4 cm (all P < .05). The adjusted probability of ICU admission and prolonged length of stay was 41% and 46% lower, respectively, for patients undergoing LRN (P < .001). Although uncommon for both groups, the adjusted probability of in-hospital mortality was 51% higher (2.3% vs 1.5%, P ¼ .04) for patients treated with a laparoscopic approach. CONCLUSIONS: At a population level, patients treated with LRN have a lower likelihood of ICU admission and prolonged length of stay, supporting the convalescence benefits of laparoscopy. In-hospital mortality, however, was higher among patients treated with LRN. The latter finding suggests a potentially unanticipated consequence of this technique and highlights the need for long-term monitoring during and after the widespread adoption of new surgical technologies. Cancer 2011;117:4184-93.