Objective:To investigate the predictive value of C-reactive protein/albumin ratio (CAR), prealbumin (PA) and neutrophil/lymphocyte ratio (NLR) for postoperative infection in patients with ankle fractures.Methods:A total of 100 patients with ankle fractures who underwent internal fixation at Wenzhou Integrated Traditional Chinese and Western Medicine Hospital between January 2016 and December 2021 were selected as the study subjects. Additionally, 100 patients who underwent routine physical examinations at the hospital during the same period were included in the healthy control group. The patients were retrospectively divided into a non-infection group ( n = 75) and an infection group ( n = 25) based on the occurrence of postoperative infection. The levels of CAR, PA, and NLR in peripheral blood were compared among the groups. The predictive efficiency of serum CAR, PA, and NLR for postoperative infection in patients with ankle fractures was analyzed using the receiver operating characteristic curve (ROC). Results:Three days after surgery, CAR and NLR in peripheral blood of the infection group were 2.28 ± 0.23 and 8.86 ± 1.27, respectively. These values were significantly higher compared with those in the healthy control group, which were 0.25 ± 0.05 and 1.95 ± 0.25, respectively ( t = 86.25, 53.38, both P < 0.001) . Additionally, the level of PA in peripheral blood of the infection group was (162.15 ± 30.86) mg/L, which was significantly lower than that in the control group [(208.03 ± 39.09) mg/L, t = 9.21, P < 0.001]. CAR and NLR in the peripheral blood of patients in the infection group were 2.35 ± 0.29 and 9.83 ± 1.70, respectively. These values were significantly higher than those in the non-infection group (2.12 ± 0.07, 7.62 ± 0.85, t = 6.39, 8.55, both P < 0.001). The level of PA in the peripheral blood of patients in the infection group was (132.82 ± 25.20) mg/L, which was significantly lower than that in the non-infection group [(168.06 ± 31.19) mg/L, t = 5.11, P < 0.001]. The receiver operating characteristic curve analysis revealed that the area under the curve (AUC) was 0.809 for CAR, 0.781 for CRP, and 0.777 for NLR. When the three markers were used in combination, the AUC increased to 0.893. The AUC value for the combined markers was significantly higher than those for CAR, PA, and NLR alone (all P < 0.05). Conclusion:The values of CAR and NLR in peripheral blood increase in patients with ankle fractures who develop post-surgical infections, whereas the level of PA decreases. Among these markers, CAR exhibits the highest predictive value for postoperative infection in ankle fractures. Furthermore, the combined use of these three markers can significantly enhance the predictive efficiency.