Background: Three premises underlie this formulation of an algorithm: 1) there is no gold standard operation; 2) the bariatric surgeon should be able to perform more than one bariatric operation; and 3) a patient can be broadly matched to an operation. Methods: Literature review and interpretation. Results: The 5 currently clinically-tested bariatric procedures, ranked from least to most weight loss, are: 1) gastric banding (GB); 2) vertical banded gastroplasty (VBG); 3) Roux-en-Y gastric bypass (RYGBP); 4) biliopancreatic diversion (BPD) or duodenal switch (DS); and 5) long-limb Roux-en-Y gastric bypass (LLRYGBP). The following diagram for decision-making takes into consideration body mass index (BMI); age; gender, race, and body habitus (GRH); and comorbidities (CoM): [GRAPHICS] This diagram can be converted to an equation; OC -1.0+BMI Number (1 to 6)+/-0.5 (age<40>)+/-0.5 (GRH, Favorable or Unfavorable) +/-l (CoM, Low or High), where OC=operative category: GB=0 to 3, VBG=2 to 5, RYGBP=3 to 6, BPD/DS=4 to 7, and LLRYGBP=6 to 9. Overlap between OCs integers allows for surgeon and patient preference. Conclusions: A diagram or equation algorithm for operative selection in the morbidly obese has been constructed.