BACKGROUND: Infection after total hip arthroplasty remains a diagnostic challenge. We assessed the accuracy of computed tomography (CT)-guided joint aspiration combined with CT findings for prediction of septic hip prosthesis before revision surgery. METHODS: A total of 96 patients (64.6% men; mean age, 68 years) scheduled for elective revision surgery due to suspicion of infection after total hip arthroplasty underwent CT-guided joint aspiration. Volume and microbiological cultures of aspirated fluid and salient findings on CT scans, including periprosthetic soft-tissue mass, malpositioning of the prosthesis, periprosthetic osteolysis, reactive enlarged lymph nodes, and heterotopic ossification, were assessed by a blinded radiologist. RESULTS: Septic hip prosthesis was shown on revision surgery in 35 patients (36.4%), with Staphylococcus epidermidis isolated in 54.3% of cases. Culture of the aspirated fluid yielded the same microorganism in 24 patients (68.6%). The accuracy of preoperative CT-guided joint aspiration was 86.5%. High volume (>1 mL) of aspirated fluid was recorded in 32 patients (33.3%). In the multivariate analysis, high volume on CT aspiration, accumulation of soft tissue exceeding the joint margin, osteolysis without bone insufflation, and enlarged iliac lymph nodes were significant predictors of infected hip prosthesis. Similar results were obtained after adjustment of the model by the presence of aggressive granulomatosis. CONCLUSION: Preoperative CT-guided joint aspiration is accurate to diagnose septic hip prosthesis based on CT imaging findings and volume and bacterial culture of the aspirated fluid. Enlarged iliac lymph nodes emerged as a strong predictor of infection.