During the one-leg standing test (OLS) the time of maintain this position by the patients was measured. The placement of the limbs was the same as in the case of the balance platform test. Subjects performed 3 trials on each lower limb. Time ended when subject either: loosed balance and touched raised foot the floor, moved supporting leg on the ground, a significant loss of balance or a maximum of 60 s had elapsed. Results achieved by the subjects after THR on both operated (OLS-O) and non operated limbs (OLS-N) were compared with the index of the control group (OLS-C: mean result of the tests performed on the left and right legs).