Abstract:[Objective] To compare the perioperative clinical and laboratory test outcomes of total knee arthroplasty (TKA) for rheuma- toid arthritis (RA) and osteoarthritis (OA) . [Methods] From March 2019 to September 2019, 115 patients who underwent unilateral TKA for RA or OA in our hospital, and had complete perioperative clinical and laboratory data were included in this study. The clinical and laborato- ry data of the two groups were compared. [Results] All patients in both groups were successfully operated on, without serious complications. Although there was no significant difference in operation time and incision length between the two groups (P>0.05) , the RA group had signif- icantly greater intraoperative blood loss than the OA group (P<0.05) . The RA group was marked significantly higher VAS score than the OA group at 3 days after operation (P<0.05) . In terms of laboratory test, the D-dimer (DD) and fibrinogen (FIB) in both groups increased at 3 days after operation compared with those before operation, whereas which was not statistically significant (P>0.05) , by contrast, the erythro- cyte sedimentation rate (ESR) and C-reactive protein (CRP) significantly increased in both groups (P<0.05) . The RA group had significantly higher preoperative DD and FIB than the OA group (P<0.05) , nevertheless which became not statistically significant between the two groups 3 days after operation (P>0.05) . However, the RA group had significantly higher ESR and CRP than the OA group preoperatively and 3 days postoperatively (P<0.05) . [Conclusion] TKA does effectively treat both RA and OA. In contrast, the RA has significantly greater intraopera- tive blood loss than the OA, which might be related to the significantly higher inflammatory marker in the RA over the OA.