This study evaluated the effectiveness of manual lymphatic drainage (MLD) in the prevention of secondary lymphedema after treatment of breast cancer. The study consisted of 67 women, who underwent breast surgery for primary breast cancer. From the second day of surgery, 33 randomly chosen women were given MLD. The control group consisted of 34 women who did not receive MLD. Measurements of the volumes of both the arms were taken before surgery and on days 2, 7, 14, and at 3 and 6 months after surgery. At 6 months after breast cancer surgery, among the women who did not undergo MLD, a significant increase in the arm volume on the operated side was observed (p=0.0033) when compared with the arm volume before surgery. At this time, there was no statistically significant increase in the volume of the upper limb on the operated side in women who underwent MLD. This study demonstrates that regardless of the surgery type and the number of the lymph nodes removed, MLD effectively prevented lymphedema of the arm on the operated side. Even in high risk breast cancer treatments (operation plus irradiation), MLD was demonstrated to be effective against arm volume increase. Even though confirmatory studies are needed, this study demonstrates that MLD administered early after operation for breast cancer should be considered for the prevention of lymphedema.