The aim of this systematic review and meta-analysis was to examine the efficacy, anti-effect of ketamine (intervention) for post-traumatic stress disorder (PTSD) patients during analgesia proceeding and mental illness treatment methods, in comparison with control (midazolam, opioid, saline or placebo). The bibliographic databases Cochrane, Embase, Pubmed and Web of Science were searched from inception to 23 May 2021 for randomized controlled trials, case-control and cohort studies included. For continuous and dichotomous outcomes, respectively, we calculated the mean difference using the inverse-variance method and the risk ratio with the Mantel-Haenszel method. In all, ten trials with 705 patients were included. Confirmed by meta-analysis, ketamine didn't increase the prevalence of PTSD by a risk ratio (95 % CI) of 0.86 (0.61 to 1.20), p = 0.38 in 3 trials with 503 patients. Evidence of a difference was found in the PTSD-scales taken between ketamine and control during short durations (months), with a mean difference (95 % CI) of 2.45 (1.33 to 3.58), p < 0.001 in three trials with 65 patients. Another evidence is shown in chronic PTSD (years), with a mean difference (95 % CI) of -3.66 (-7.05 to -0.27), p = 0.03 in three trials with 91 patients. Sub-group analysis underlined the increased benefit of ketamine administration for those in whom the procedure was more than one week in the chronic PTSD group. The adoption of ketamine for the short duration of PTSD is in avoidance, but for chronic PTSD is recommended and, in the opinion of the authors, should be considered as a new therapy in view of its potential to ameliorate arousal, avoidance and dissociative symptoms, neuroticism after trauma needing more animal research and clinical trials.