Fracture-related infection (FRI) is a common complication associated with orthopaedic fracture care. Diagnosing these complications in the preoperative setting is difficult. Platelets are a known acute phase reactant with indices that change in accordance with infection and inflammation. The purpose of our study was to assess the diagnostic utility of platelet indices at assessing FRI. A retrospective review performed for all patients who underwent revision surgery for fracture nonunion between 2013 and 2018. Radiographs were employed to define nonunion. Intraoperative cultures were used to define FRI. Receiver operator characteristic (ROC) curve analysis was used to assess the diagnostic ability of preoperative erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and the platelet count/mean platelet volume ratio (P/V) at recognizing FRI. Of the 53 revision surgeries that were performed for fracture nonunion, 17 (32.1%) were identified as FRI. There were no significant demographic differences between the two cohorts. Patients with FRIs exhibited higher values for ESR (54.82 vs. 19.16, p<0.001), CRP (0.90 vs. 0.35, p=0.003), and P/V (37.4 vs. 22.8, p<0.001) as compared to those within the aseptic nonunion cohort. ROC curve analysis for P/V demonstrated that at an optimal ratio of 23, area under the curve (AUC) is 0.814, specificity is 55.6%, and sensitivity is 100.0%. There was no significant difference in the diagnostic performance of the serum biomarkers but only ESR and P/V had an AUC greater than 0.80. The negative predictive value (NPV) for P/V, ESR, and CRP was 100.0%, 84.6%, and 78.6%, respectively. The P/V ratio may serve as a reliable screening test for FRI.© The author(s).