Aims. To study the safety of autotransfusion following local infiltration analgesia (LIA) with ropivacaine. Background. Knowledge of blood concentrations of ropivacaine after LIA and autotransfusion is crucial. However, very limited data are available for toxicological risk assessment. Methods. Autotransfusion was studied in patients after total knee arthroplasty (TKA: n = 25) and total hip arthroplasty (THA: n = 27) with LIA using 200mg ropivacaine, supplemented with two postoperative bolus injections (150mg ropivacaine). Drainage blood was reinfused within 6h postoperatively. Results. Reinfusion caused a significant increase in the serum concentration of total ropivacaine for TKA from 0.54 ± 0.17 (mean ± SD) to 0.79 ± 0.20μg/mL (P < 0.001) and a nonsignificant increase for THA from 0.62 ± 0.17 to 0.63 ± 0.18μg/mL. The maximum free (unbound) concentration after reinfusion was 0.038μg/mL. Peak total and free venous ropivacaine concentrations after 8h and 16h postoperative bolus injections were 2.6μg/mL and 0.11μg/mL, respectively. All concentrations observed were below the threshold for toxicity and no side effects were observed. Conclusion. Autotransfusion of patients undergoing knee or hip arthroplasty after local infiltration analgesia with 200mg ropivacaine can be performed safely, even supplemented with 8h and 16h postoperative bolus injections.