BACKGROUND: To assess whether insurance status has an effect on emergency department (ED) length of stay (LOS) and likelihood for admission or transfer to an operating room. METHODS: This was a retrospective cross-sectional study of all encounters from January 2011 through October 2013 at an urban, academic trauma center. Analysis included multi-variable linear regression for ED LOS and logistic regression for the likelihood of admission. RESULTS: Overall, 201535 patients met the inclusion criteria, for which the mean age was 43.8 years, 55.9％ were female, 23.4％ were uninsured and 8％ were of non-black race. Admission rate was 24.5％ and operative rate was 1.4％. After adjusting for age, sex, triage acuity and race, the presence of insurance coverage was associated with an increased ED LOS of 575 (95％CI 552–598) vs. 567 (95％CI 543–591) minutes (P<0.01) among admitted patients and a decreased ED LOS of 456 (95％CI 381–531) vs. 499 (95％CI 423–575) minutes (P<0.01) among those transferred to an operating room. Adjusting for these same predictors, insured status remained a predictor for admission (odds ratio 1.24, 95％CI 1.20–1.28, P<0.01) and a negative predictor for transfer to the operating room (odds ratio 0.84, 95％CI 0.77–0.92, P<0.01). CONCLUSION: The insured experienced a clinically insignificant increase in ED LOS when admitted and a 43-minute decrease in ED LOS when being transferred to the operating room. The insured were more likely to be admitted and less likely to be transferred to an operating room.