OBJECTIVES: In this study, we quantify common complications that happen within 30 days of bariatric surgery, determine if risk of complication depends on the type of bariatric procedure, and identify risk factors for each procedure type.  METHODS: Medical claims data were used to obtain information on 5,527 patients in the southeastern PA region who had one of three bariatric procedures between January 2009 and May 2012. Relevant pre-existing medical conditions and common complications within 30 days of surgery were identified by diagnosis and procedure codes from claims. Logistic regression models were used to determine significant predictors of having a complication, controlling for factors such as age, gender, illness burden, and facility effects.  RESULTS: There were 5,527 surgeries, of which 60% were gastric bypass, 29% were adjustable band, and 11% were gastric sleeve procedures.  The most common complications within 30 days of surgery were nausea and vomiting, anastomatic leakage, intestinal obstruction, dehydration, and vitamin deficiency. After controlling for factors such as age, gender, illness burden, and facility, patients undergoing gastric bypass or gastric sleeve had significantly greater odds of developing complications than patients who had the adjustable band.  The strongest predictors for complications for gastric bypass were a history of COPD, hypertension, or deep venous thrombosis/ pulmonary embolism. For gastric sleeve, depression was a significant risk factor, and for the adjustable band, a history of COPD, deep venous thrombosis/pulmonary embolism, or type II diabetes were significant risk factors.  CONCLUSIONS: The type of procedure (gastric bypass, gastric sleeve, or adjustable band) plays a significant role in the risk for complications within 30 days of bariatric surgery, with gastric bypass and gastric sleeve procedures having greater odds of complication than the adjustable band procedure. Certain pre-existing conditions such as COPD and deep venous thrombosis/pulmonary embolism also increase the odds for complications.