['There is little known about any change in postural balance caused by asymmetrical volume increase due to unilateral upper extremity lymphedema in patients who underwent breast surgery. The aim of this study was to determine whether there is a change in postural balance by measuring postural sway velocity (PSV), center of gravity (CoG) displacement and directional control (DCL) in patients with unilateral upper extremity lymphedema in breast cancer survivors.', 'Eighteen females 38-60 (M = 53) years old diagnosed with upper extremity lymphedema due to breast cancer surgery, and 18 healthy females with similar ages (M = 52.5) were assessed using the Balance Master system (Neuro Com, Clackamas, USA). Unilateral stance (US) and bilateral stance (BS) tests in eyes open and closed conditions and the limit of stability (LOS) test were applied to quantify postural sway velocity (PSV), CoG displacement, and directional control (DCL).', 'The lymphedema group showed a significant increase in PSV in the US test on the ipsilateral leg with eyes open (p = 0.02) and eyes closed (p = 0.005) as well as on the contralateral leg with eyes open (p = 0.004) and eyes closed (p = 0.0001). Average displacement and position of the CoG were 25% of LOS (p = 0.0001) towards the lymphedema side and 60.6 degrees respectively. DCL in the lymphedema group was significantly lower in forward (p = 0.0001), back (p = 0.003), ipsilateral (p = 0.002), and contralateral (p = 0.03) directions.'] Does unilateral upper extremity lymphedema deteriorate the postural stability in breast cancer survivors?