Authors performed a retrospective clinical and radiologic comparative study for 43 uncemented primary total hip arthroplasty which include 20 hips without lateral porous pad and 23 hips with lateral porous pad in same kinds of implant(Zimmer Anatomic") to investigate the role and significance of the lateral porous pad. The average follow up was 35 months and 38 months for without and with lateral porous pad respectively. The results were as followings: 1. Clinical and radiological results of group with and without lateral pad were similar together except incidence of radiolucency at zone 1 on anteroposterior radiograph in group without lateral pad was markedly higher compare to that in group with lateral pad. 2. The extent of lateral porous pad was not sufficiently enough to make better clinical and radiological results in stem with lateral pad compare to stem without lateral pad. 3. Stems without lateral porous pad had no evidence of bone ingrowth on lateral pad while stems with lateral pad had bone ingrowth on lateral pad with more than 50% in incidence. So, we think that presence and increase of extent of porous pad would have better clinical and radiological results.