Objective: The purpose of this study was to investigate the effect of the falls on the center of pressure (CoP) complexity during gait using non-linear approximate entropy (ApEn). Method: 20 elderly women with experience of falling (age = 72.55 ± 5.42 yrs; height = 154.40 ± 4.26 cm; body weight = 57.40 ± 6.21 kg; preferred gait speed = 0.52 ± 0.17 m/s) and 20 elderly women with no experience of falling (age = 71.90 ± 2.90 yrs; height = 155.28 ± 4.73 cm; body weight = 56.70 ± 5.241 kg; preferred gait speed = 0.56 ± 0.13 m/s) were recruited for the study. While they were walking at their preferred gait speed on a treadmill (instrumented dual belt treadmills, Bertec, USA) with a force plate CoP data were collected for the 20 strides. The complexity of the CoP was analyzed using the ApEn technique. Results: The ApEn of the medial-lateral CoP in the fallers showed smaller about 16% compared to the non-fallers (p<.05). The ApEn of the antero-posterior CoP of the fallers showed smaller about 12% compared to the non-fallers, but the difference was not statistically significant. Conclusion: Based on the results of this study, the reduction of the medio-lateral CoP complexity in the elderly gait would be an index to determine the potential fall.