PURPOSE: The purpose of this study was to compare the effectiveness of a structured preoperative PCA education to that of the usual informal teaching provided by hospital staff in alleviating postoperative pain through more effective use of PCA therapy. METHOD: As an advanced research, the knowledge about the use of PCA therapy and the attitude about the use of the pain medicine were estimated, and then as a later research, the knowledge about the use of PCA therapy, the attitude about the use of the pain medicine, and the score of the pain were estimated. RESULT: The experimental group those who received structured preoperative PCA education had statistically significant higher knowledge regarding the use of PCA therapy(p=0.026) and more positive attitudes toward using pain medicine(p=0.004). The experimental group those who received structured preoperative PCA education reported better pain control 4(p= 0.002), 8(p=0.014) and 24 hours(p=0.018) after the operation. CONCLUSION: The structured preoperative PCA education increases the knowledge for the use of patient's PCA therapy and changes their attitude toward the use of the pain medicine positively and consequently enable the use of PCA therapy to be more effective and then finally reduced the patient's pain after the operation.