To fill a void in the literature, we performed a literature search and subsequently reviewed randomized controlled trials (RCTs) in the field of obesity surgery that were published over the past 40 years. All RCTs published in the English between January 1972 and December 2011 were identified through a literature search using the PubMed database. The following search terms were used: "bariatric surgery", "obesity surgery", and "weight reducing surgery". Studies of basic science and anesthesia-related pain management were excluded. The extracted trials were divided into four groups: comparisons of different interventions, intraoperative surgical techniques, preoperative evaluation, and postoperative care. The literature search produced 753 manuscripts, of which 168 met the eligibility criteria. Among 168 papers, 32 % compared different interventions, 48 % assessed intraoperative surgical techniques, 18 % assessed postoperative care, and the remaining 2 % assessed preoperative evaluation. The RCTs were published in 47 different journals, most commonly in Obesity Surgery (28.6 %) and the Annals of Surgery (11.9 %). Trials were conducted in 25 different countries, with the greatest contribution from the USA (35.1 %). There was a progressive increase in published trials from 1972 to 2011, with 119 RCTs (70.8 %) being published over the last decade. A trend for an increasing number of published RCTs in the field of bariatric surgery was observed over the recent years. Although data from large, adequately powered, long-term RCTs are still lacking, any surgical intervention appears to be more effective than medical care for the treatment of morbid obesity.