Introduction: Today, hysterectomy is one of the commonest types of surgery and is the one of the most prevalent surgical procedures in the United States after cesarean section (C-section). One of the important complications of hysterectomy is postoperative pain. To relieve this pain, various methods are used, including the use of analgesics such as intraperitoneal ketamine, dexmedetomidine and bupivacaine. Therefore, the present study is aimed to conduct a comparative study on the effect of intraperitoneal ketamine, dexmedetomidine and bupivacaine on postoperative pain control in patients undergoing abdominal hysterectomy. Materials and Methods: The present study is a randomized, double-blind clinical trial which performed on 105 patients during March 2019 to June 2020, undergoing abdominal hysterectomy who were randomly divided into three groups including D (dexmedetomidine), K (ketamine) and B (bupivacaine). The study groups were compared in terms of hemodynamics, postoperative pain score and amount of drug used after 24 hours after surgery, as well as duration of postoperative analgesia. The obtained data were statistically analyzed using Spss 22 statistical software using ANOVA and T test. Results: The results of this study revealed the effect of intraperitoneal dexmedetomidine, bupivacaine and ketamine in controlling the pain following abdominal hysterectomy, among which intraperitoneal ketamine was more effective in controlling postoperative pain, increasing postoperative pain relief, and reducing postoperative opioid use when compared with dexmedetomidine and bupivacaine. Conclusion: All three drugs, intraperitonealdexmedetomidine, bupivacaine and ketamine, were detected to be essential in controlling postoperative pain in patients with complete abdominal hysterectomy. However, the effect of intraperitoneal ketamine was found to be greater than that of the other two drugs.