Patients who undergo total joint arthroplasty and are destined for discharge to an extended-care facility--particularly Medicare beneficiaries--are required to have an inpatient stay of at least 3 consecutive days. The primary objective of this study was to explore the effect of this policy on length of stay. Secondary outcomes were 30-day readmission rate and inpatient rehabilitation gains. We retrospectively reviewed 284 consecutive cases of patients who underwent primary total hip or knee arthroplasty and were discharged to an extended-care facility. Based on readiness-for-discharge criteria, delaying discharge until postoperative day 3 increased length of stay by 1.08 days (P < .001) and had no effect on risk for 30-day readmission (P = .073). Although rehabilitation status improved with stays past discharge readiness (P = .038), the gains were not clinically sufficient to affect discharge destination. This study calls into question the validity of Medicare's 3-day rule in primary total joint arthroplasty. Larger, prospective, multicenter studies are needed to confirm these findings.