Objective:To evaluate the value of serum protein electrophoresis in the diagnosis of periprosthetic joint infection (PJI) after hip and knee arthroplasty.Methods:The data of 171 patients who underwent one side hip or knee revision surgery in the affiliated Hospital of Qingdao University from August 2013 to June 2019 were analyzed retrospectively. According to the reasons for revision, 55 patients in PJI group, 29 males and 26 females, aged 67.38±9.60 years, 26 hips and 29 knees, were classified as Tsukayama type IV; Aseptic loosening (AL) group consisted of 116 patients, 67 males and 49 females, aged 69.69±9.20 years, 97 hips and 19 knees .The ratios of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), D-dimer, fibrinogen, serum total protein, serum albumin, serum globulin and serum protein electrophoresis bands in the two groups were statistically analyzed. The sensitivity and specificity of each index were calculated according to the receiver operating characteristic (ROC) curve, and the diagnostic value was compared according to the area under the curve (AUC).Results:There was no significant difference in age, sex or body mass index (BMI) between PJI group and AL group ( P>0.05), but there was significant difference in joint type with 26 hips and 29 knees in PJI group, 97 hips and 19 knees in AL group (χ 2=24.41, P<0.001). The proportion of α1 globulin band was 6.40% (5.30%, 8.10%) in PJI group, which increased significantly compared to 4.20% (3.90%, 4.80%) in AL group ( H=453.50, P<0.001). Albumin band was 49.00% (44.00%, 52.20%) in PJI group, which decreased significantly compared to 54.35% (51.25%, 56.70%) in AL group ( H=4 954.00, P<0.001). The AUC of CRP, ESR, D-dimer, fibrinogen, albumin band and α1 globulin band were 0.87[95% CI (0.80, 0.93)], 0.88[95% CI (0.82, 0.94)], 0.67[95% CI (0.58, 0.76)], 0.87[95% CI (0.82, 0.93)], 0.78[95% CI (0.70, 0.85)] and 0.87[95% CI (0.81, 0.93)], respectively. Conclusion:Albumin bands and α1 globulin bands in serum protein electrophoresis had high diagnostic value for PJI, and the accuracy of α1 globulin bands was as good as that of routine inflammatory markers such as CRP and ESR.