[Purpose] The current study aimed to investigate the center of pressure, as an indicator of postural sway, to determine any differences between women with clinical lumbar instability and asymptomatic low back pain. [Participants and Methods] Thirty healthy and fifteen clinical lumbar instability participants were measured for their postural sway in the anterior-posterior and medial-lateral directions. The women were tested for postural sway on a force plate in quiet standing and eyes closed. Center of pressure path length and mean velocity in the anterior-posterior and medial-lateral directions and total area of excursion were measured and analyzed for 30 seconds. [Results] Clinical lumbar instability participants showed a significantly increase when compared with healthy participants, in path length and mean velocity in both directions and total area of excursion. [Conclusion] The findings suggest that chronic low back pain patients with clinical lumbar instability have increased postural sway when vision is deprived. The clinical significance of this has not yet been determined but may provide an opportunity for therapy directed at improving balance control in this patient group.