Background: Today open Roux-en-Y gastric bypass (ORYGB) is reserved for abdomens too complex or obesity too severe for laparoscopic surgery. However, outcomes by age in ORYGB are unknown. Objective: Identify variation by age in ORYGB patients. Setting: Independent database. Methods: 5389 ORYGB BOLD patients was analyzed retrospectively by age: <30 (591), 30-40 (1252), 40-50 (1527), 50-60 (1388), 60-70 (592) and >70 (39). Statistics: ANOVA/general linear model. Results: Baseline female/male (p<0.01), weight, BMI, African-American, Hispanic, Medicaid, Private insurance, self-pay (p<0.0001), PCOS, PTC (n=10) varied inversely with age. Medicare, CHF, HTN, angina, LEE, PVD, IHD, dyslipidemia, OHS, diabetes, gout, IFS, and unemployment varied directly. Caucasian, Asian, Other race, DVT/PE, hernia, cholelithiasis, GERD, panniculitis, liver disease, SUI, MSP, fibromyalgia, alcohol and tobacco abuse, depression, PI, MHD (n=17) vary non-linearly. At 12 months, in spite of equal BMI by age, CHF, HTN, angina, PVD, dyslipidemia, cholelithiasis, SUI, diabetes, gout, IFS (n=10) varied directly. PCOS and PTC varied inversely, and LEE, OSA, hernia, MSP, tobacco abuse, depression, MHD varied non-linearly. 24 months CHF, HTN, angina, dyslipidemia, diabetes, IFS, and MSP vary directly. PTC and tobacco abuse varied inversely. LEE, OSA, PHTN, hernia, PCOS, and tobacco abuse varied non-linearly. Conclusions: ORYGB patients vary dramatically by decade of age. Pre-operatively 10 co-morbidities varied inversely, 13 directly, and 17 non-linearly by age. In spite of equal BMI by age at 24 months, important co-morbidities CHF, HTN, angina, dyslipidemia, diabetes varied directly, tobacco inversely, and OSA non-linearly. This advance clinical knowledge of age variation can aid ORYGB management