PURPOSE Robot-assisted radical prostatectomy has undergone rapid dissemination driven in part by market forces to become the most frequently used surgical approach in the management of prostate cancer. Accordingly, a critical analysis of its volume-outcome relationship has important health policy implications. Therefore, we evaluated the association of hospital robot-assisted radical prostatectomy volume with perioperative outcomes, and examined the distribution of hospital procedure volume to contextualize the volume-outcome relationship. MATERIALS AND METHODS We identified 140,671 men who underwent robot-assisted radical prostatectomy from 2009 to 2011 in NIS (Nationwide Inpatient Sample). The associations of hospital volume with perioperative outcomes and total hospital costs were evaluated using multivariable logistic regression and generalized linear models. RESULTS In 2011, 70% of hospitals averaged 1 robot-assisted radical prostatectomy per week or less, accounting for 28% of surgeries. Compared to patients treated at the lowest quartile hospitals, those treated at the highest quartile hospitals had significantly lower rates of intraoperative complications (0.6% vs 1.4%), postoperative complications (4.8% vs 13.9%), perioperative blood transfusion (1.5% vs 4.0%), prolonged hospitalization (4.3% vs 13.8%) and mean total hospital costs ($12,647 vs $15,394, all ptrend <0.001). When modeled as a nonlinear continuous variable, increasing hospital volume was independently associated with improved rates of each perioperative end point up to approximately 100 robot-assisted radical prostatectomies per year, beyond which there appeared to be marginal improvement. CONCLUSIONS Increasing hospital robot-assisted radical prostatectomy volume was associated with improved perioperative outcomes up to approximately 100 surgeries per year, beyond which there appeared to be marginal improvement. A substantial proportion of these procedures is performed at low volume hospitals.