Obese and morbidly obese patients are a growing group of individuals that generates medical, social and economicproblems worldwide. They undergo various interventions that require anesthesia and/or analgesia. Despite theirhealthy look, these individuals are graded at high ASA physical status, mainly because of their impaired respiratoryand cardiovascular conditions, and the metabolic changes their body undergoes. Opioids are the default drugsfor perioperative analgesia. Nevertheless, their use has reached a frightening epidemic-like condition worldwide.Multimodal analgesia regimens have been recommended as a perioperative standard of care, particularly useful in theobese. These regimens employ combinations of opioids and non-opioid compounds that reciprocate each analgesicpotencies, thus providing superior pain relief at rest, movement, or on effort, while reducing opioid consumption andtheir concerned adverse effects. The most important perioperative IV adjuvant currently employed is ketamine thatsees resurgence among physicians from diverse medical specialties. After summarizing obese patients’ perioperativedrawbacks, this review will illustrate ketamine’s neuropharmacology, and will describe its therapeutic usefulness asan analgesic adjuvant. Since data regarding the use of the drug in obese patients is scarce, brief exemplifications ofits benefits in non-obese cohorts will be portrayed as well.