OBJECTIVE: To estimate the rate of inpatient stay and the factors predicting inpatient status after robotic surgery for endometrial cancer following the change in the Medicare definition of "inpatient" to include hospitalization spanning 2 midnights. DESIGN: Retrospective chart review (Canadian Task Force classification II-1). SETTING: Academic hospital. PATIENTS: All patients (n = 395) with endometrial cancer who underwent robotic surgical management between 2006 and 2010. INTERVENTION: The outpatient stay group with hospitalization spanning 1 midnight was compared with the inpatient stay group with hospitalization spanning 2 midnights or longer through estimation of the adjusted relative risk (aRR) for various characteristics of interest. RESULTS: Ninety-six of 395 patients (24.3%) stayed at least 2 midnights and thus were deemed inpatients. Clinical factors associated with inpatient stay were increasing age, history of myocardial infarction (aRR, 2.0; 95% confidence interval [CI], 1.0-3.7), surgery start time at or after 12 noon (aRR, 1.7; 95% CI, 1.2-2.4), perioperative blood transfusion (aRR, 3.2; 95% CI, 2.3-4.5), and surgery performed in the year 2010 (aRR, 0.5; 95% CI, 0.3-0.7). Age ≥ 60 years was associated with at least a 2-fold adjusted risk of prolonged hospitalization. Body mass index, other medical comorbidities, operative duration, estimated blood loss, and performance of lymphadenectomy or additional surgical procedures were not identified as significant risk factors. CONCLUSION: Approximately 75% of the patients undergoing robotic surgery for endometrial cancer were discharged as outpatients. Recognition of factors predicting inpatient stay can improve hospital resource allocation and throughput in women undergoing robotic surgery for endometrial cancer.