24:T413,Visual abstract for the following written abstract: Background: Same-day discharge (SDD) following primary total knee arthroplasty (TKA) offers significant clinical and economic benefits. Objectives: This study identified factors associated with successful same-day discharge and total length of stay after TKA. Methods: Logistic and linear regression analyses were performed on data extracted from the electronic medical record. Results: Female sex (OR 0.54, CI: 0.44 - 0.66, p<0.001), GFR<60 ml/min/1.73 m2 (OR 0.54, CI: 0.38 - 0.77, p<0.001), surgery start in the afternoon (OR 0.24, CI: 0.19 - 0.31, p<0.001) or late afternoon (OR 0.04, CI: 0.01 - 0.08, p<0.001) compared to a morning start, as well as increasing Elixhauser score (OR 0.89, CI = 0.85 - 0.93) and each 10-minute increase in surgery duration (OR 0.83, CI: 0.78 - 0.87, p<0.001), all decreased the likelihood of same-day discharge. Patients receiving intraoperative periarticular morphine (OR 2.09, CI: 1.22 - 3.56, p=0.007) were more likely to be discharged on the same day.25:T413,Visual abstract for the following written abstract: Background: Same-day discharge (SDD) following primary total knee arthroplasty (TKA) offers significant clinical and economic benefits. Objectives: This study identified factors associated with successful same-day discharge and total length of stay after TKA. Methods: Logistic and linear regression analyses were performed on data extracted from the electronic medical record. Results: Female sex (OR 0.54, CI: 0.44 - 0.66, p<0.001), GFR<60 ml/min/1.73 m2 (OR 0.54, CI: 0.38 - 0.77, p<0.001), surgery start in the afternoon (OR 0.24, CI: 0.19 - 0.31, p<0.001) or late afternoon (OR 0.04, CI: 0.01 - 0.08, p<0.001) compared to a morning start, as well as increasing Elixhauser score (OR 0.89, CI = 0.85 - 0.93) and each 10-minute increase in surgery duration (OR 0.83, CI: 0.78 - 0.87, p<0.001), all decreased the likelihood of same-day discharge. Patients receiving intraoperative periarticular morphine (OR 2.09, CI: 1.22 - 3.56, p=0.007) were more likely to be discharged on the same day.