ObjectiveTo explore the effects of postoperative magnesium sulphate on pain relief after open gynecological surgery. MethodsSixty women who were diagnosed as hysteromyoma in Lucheng People' Hospital in Wenzhou city and underwent open hysterectomy from July 2011 to May 2012 were randomly divided into two groups (30 women in each group). Applying epidural administration of magnesium sulfate, the magnesium sulfate group (n=30) was given 500 μg magnesium sulfate and 1 mg morphine, while the control group (n=30) was only given 1 mg morphine. Pain scores (at 2 h, 4 h, 8 h, 16 h and 24 h, respectively) as well as complications were observed. Plasma levels of β-endorphin (β-EP) (in 4 h and 24 h, respectively) and the first time when needs postoperative analgesia were recorded. ResultsCompared with the control group, pain scores during 24 h after operation, levels of β-EP at 4 h and 24 h, and the first time for postoperative analgesia were better improved in the magnesium sulfate group. ConclusionEpidural administration of magnesium sulfate combined with morphine is an effective and safe method to improve the effects of postoperative magnesium sulphate on pain relief after open gynecological surgery.