Objective: The aim of this study is to compare the blood loss and complications between simultaneous bilateral total knee replacement (SBTKR) and unilateral total knee replacement (UTKR).

Methods: 30 SBTKRs and 55 UTKRs performed between March 2023 and March 2024 were included in this study. Haematocrit, D-dimer, haemoglobin, blood loss, blood transfusion, and complications were compared between the groups.

Results: Haemoglobin between the groups was not significantly different (P > 0.05). In the SBTKR group, the haematocrit on the 3rd postoperative day was lower (P < 0.05). The total drain output of the UTKR group was not significantly different from any unilateral side of the SBTKR group (P < 0.05). The mean RBC transfusion requirement was higher in the SBTKR group than in the UTKR group (P <0.001). The total drainage of the SBTKR group was significantly more than the UTKR group, but the total drain output of the UTKR group was not significantly different from any unilateral side of the SBTKR group (P> 0.05).