Introduction: Acute postoperative pain is a complex problem given the pathophysiological characteristics, increasing health costs and complications and hindering recovery[1], [2].Spinal arthrodesis is one of the most painful surgical procedures, presenting intense and disabling pain[3], [4].Multimodal analgesia has been the tool with the best results, based on opioids; however, the combined use of drugs and dependence on opiates are important consequences.Therefore, the analgesic behavior during the use of subanesthetic doses of ketamine is described in the patients undergoing this procedure.Methodology: A prospective case series study was conducted from January-December 2019, with patients undergoing spinal arthrodesis who met the inclusion criteria, at the Hernando Moncaleano Perdomo University Hospital, Neiva.A univariate statistical analysis of all the variables is performed, with a joint interpretation of the results.Results: A total of 17 patients underwent surgery,