53 patients undergoing total hip arthroplasty with the anterolateral approach were randomized to receive a psoas compartment block during surgical access in a multimodal postoperative analgesia regimen, or not. Pain, time to request for breakthrough analgesia, and mobility were assessed during the immediate postoperative period. The results indicated that pain was significantly lower in the group which received the block at postoperative hours 2, 10 and 20, and had a longer time following surgery until breakthrough analgesia was requested. There was no significant difference between groups in mobility on the first postoperative day.