Social determinants of health (SDOH) including insurance and substance use affect 50-90% of health outcomes, yet there remains no standard means to quantify or predict their impact. We prospectively evaluated the effects of SDOH on length of stay (LOS) and readmissions among emergency general surgery (EGS) and trauma patients. We compared these outcomes with Medicare Diagnosis Related Group (DRG) data to better quantify the impact of SDOH. Adult (≥18years old) EGS/trauma patients admitted July 7-28, 2020 at a Level 1 trauma center were prospectively enrolled. Primary outcomes were overall LOS, one-year readmissions, and excess LOS (eLOS), defined as days beyond DRG mean LOS. Assessment of SDOH among the 52 patients enrolled revealed that 5.8% of patients were homeless; 26.9% experienced substance abuse; 13.5% were uninsured on admission; and 7.7% on discharge. Mean LOS was 5 ± 4days; 1-year readmission rate 25.0%; eLOS mean 1.75 ± 2.4days. LOS was associated with substance use (OR 70.6 95% CI 11.7-160.4). eLOS was associated with substance use (OR 6.1, 95% CI 1.5-25.1) and public or no insurance (OR 26.0, 95% CI 4.9-138.1). No correlations were found between SDOH and readmission rates. EGS and trauma patients experience high rates of negative SDOH which affect clinical outcomes including LOS and readmissions. Medicare DRG determined eLOS is a fiscally relevant measure of the impact of SDOH and differs from LOS and readmissions. Further investigation is required to determine if eLOS can delineate the effects of other SDOH on admission outcomes for this patient population.