Background Length of stay after total hip arthroplasty (THA) has decreased over the last two decades. However, published studies that have examined same-day and early discharge protocols after THA have been done in highly selected patient groups operated on by senior surgeons in a nonrandomized fashion without control subjects.Questions/purposes The purpose of this study was to evaluate and compare patients undergoing THA who are discharged on the same day as the surgery (''outpatient,'' less than 12-hour stay) with those who are discharged after an overnight hospital stay (''inpatient'') with regard to the following outcomes: (1) postoperative pain; (2) perioperative complications and healthcare provider visits (readmission, One of the authors (AFC) has received research support funding from 3M (Maplewood, MN, USA) and Myoscience (Fremont, CA, USA). One of the authors (WGH) has received research support funding from DePuy (DePuySynthes, New Brunswick, NJ, USA), Biomet (Warsaw, IN, USA), and Nimbic Systems (Stafford, TX, USA). The institution of one or more of the authors (NG, SEP, RHH, WGH) has received, during the study period, funding from the Inova Health System (Falls Church, VA, USA). One of the authors (NG), or a member of his immediate family, has or may receive payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from Cayenne Medical (Scottsdale, AZ, USA) and Stryker Orthopedics (Mahwah, NJ, USA). One of the authors (AFC), or a member of her immediate family, has or may receive payments or benefits, during the study period, an amount of less than USD 10,000 from ACI Clinical (Bala Cynwyd, PA, USA). One of the authors (WGH), or a member of his immediate family, has or may receive payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from DePuy, Biomet, and Nimbic Systems. One of the authors (WJH), or a member of his immediate family, has or may receive payments or benefits, during the study period, an amount of USD 100,001 to USD 1,000,000 from Stryker. One of the authors (NG) lists the following relevant financial activities outside of this work and/or any other relationships or activities that readers could perceive to have influenced, or that give the appearance of potentially influencing, this manuscript: Data Trace Publishing Company (Towson, MD, USA) in the amount of USD 10,000 to USD 100,000. One of the authors (AFC) lists the following relevant financial activities outside of this work and/or any other relationships or activities that readers could perceive to have influenced, or that give the appearance of potentially influencing, this manuscript: SLACK Incorporated (Thorofare, NJ, USA) in the amount of less than USD 10,000. (3) relative work effort for the surgeon's office staff. Methods A prospective, randomized study was conducted at two high-volume adult reconstruction centers between July 2014 and September 2015. Patients who were younger than 75 years of age at surgery, who could ambulate without a walker, who were n...