BACKGROUND: Morbid obesity is the leading public health crisis in the United States with bariatric surgery as the only effective and enduring treatment. In other surgeries, it has been demonstrated that insurance status may affect outcomes. We hypothesize that Roux-en-Y gastric bypass (RNYGB) patients with different types of insurance will have differing long-term outcomes. METHODS: Demographic, pre-operative, and 12 month post-operative data were collected on 750 consecutive laparoscopic RNYGB patients at an academic medical center with a single surgeon. Patients were divided into private insurance (PI), Medicare (M), and MediCal (MC) groups. Variables including age, sex, race, income, body-mass index (BMI), complication and comorbidity rates, and standard lab data at pre-op and 12 months post-op were analyzed with a one way ANOVA for continuous variables and chi-square analysis for dichotomous variables.RESULTS: Significant pre-op demographic differences existed with the Medicare group being older (PI=44 yrs, M=50, MC=38)and having higher percent whites (PI=80%, M=85%, MC=61%), higher pre-op BMI (PI=47, M=51, MC=49), and higher pre-op prevalence of depression (PI=37%, M=88%, MC=49%) and hypertension (PI=55%, M=79%, MC=51%). The MediCal group had the highest percent female (PI=80%, M=88%, MC=92%). At 12 months post-op, patients with private insurance had the lowest BMI (PI=31, M=36, MC=32), the lowest complication rate (PI=13.5%, M=14.6%, MC=13.6%) and at 12 months the largest improvement in CRP (PI=396%, M=315%, MC=319%). Medicare patients saw the greatest 12 month percent improvement in both hemoglobin A1C levels (PI=13%, M=18%, MC=9%) and HDL (PI=20%, M=33%, MC=16%). CONCLUSIONS: In this study, the type of insurance correlates with both demographics and outcomes of patients undergoing RNYGB. While all patients had significant weight loss and comorbidity resolution, patients with private insurance responded best to RNYGB, having the greatest percent of excess weight lost and the best resolution of comorbidities.