The present study was undertaken to serially observe gait of patients after hip arthroplasty, using quantitative gait analysis, and to compare it between patients after total hip arthroplasty (THA) and those after bipolar endoprosthetic arthroplasty (BEA). The subjects were 53 women with unilateral osteoarthritis of the hip. Thirty-one of them underwent THA (mean age: 59.5 years) and 22 underwent BEA (mean age: 58.0 years). The stance time and characteristic parameters calculated from the vertical component of floor reaction force (FRF) were analyzed by use of FRF plate. The stance time, which indirectly represents the walking speed, tended to decrease for one year after THA and for 3 years after BEA. The decrease in this parameter was greater on the unaffected side than on the affected side. The deceleration effect and the weighing-off effect are indicators useful for observation of gait recovery. Significant differences in these indicators between the unaffected and affected sides were seen for one year after THA and 3 years after BEA. This indicates that cadence and balance of the gait recovers earlier after THA than after BEA.