Purpose: Patient-controlled epidural analgesia (PCEA) is an effective method for controlling post surgical pain. However, it is associated with adverse drug reactions such as nausea and vomiting. In this, study we tested the effects of Nei-Guan (P6) acupressure on PCEA-associated nausea, vomiting, and pain in geriatric patients after total knee replacement arthroplasty (TKRA). Methods: Ninety-nine patients who had TKRA for the first time were randomly assigned to either, experiment group (n=50) or control groups (n=49). All patients received PCEA immediately after surgery, but acupressure on Nei-Guan (P6) point was applied to experiment group only. Ten minutes of finger acupressure on Nei-Guan (P6) acupressure point was applied twice with 15 minute-interval in the experiment group. The incidence of nausea, vomiting, and retching as well as pain intensity were assessed at 12 and 24 hours after surgery. Nausea, and vomiting were assessed by Index of Nausea, Vomiting and Retching (INVR) questionnaire. Pain intensity was measured with frequency of analgesics. Results: Vomiting both was significantly different between two groups at 12 hours (t=-2.18, p=0.03) and 24 hours (t=-2.64, p=0.01) after surgery. Total scores of nausea, vomiting and retching in experimental group was significantly lower than control group 24hours after surgery (t=-2.18, p=0.03). However, pain was not different between two groups. Conclusion: Nei-Guan (P6) acupressure may be considered as an effective nursing intervention to decrease PCEA-associated nausea and vomiting in older patients after TKRA.