AIM: To explore the risk factors predicting haemoglobinuria after ultrasound-guided percutaneous microwave ablation (MWA) of liver tumours and discuss the treatments and outcomes. MATERIALS AND METHODS: The present study comprised 2,829 patients admitted for liver tumours treated with MWA from Jan 2011 to April 2017. Ethics committee approval was waived and informed consent for treatment procedures were obtained from the patients. Haemoglobinuria after MWA was found in 149 patients. The influence of 19 risk factors was assessed. Binary logistic regression and receiver operating characteristic (ROC) curve analysis were used for statistical analysis. The treatments and outcomes of patients with haemoglobinuria were summarised. RESULTS: By univariate analysis, histopathology, liver cirrhosis, MWA volume, MWA energy, and MWA duration were significant risk factors. By multivariate analysis and ROC curve, MWA energy, duration, and volume were identified as predictors of haemoglobinuria after MWA. Drug treatments including kidney protection, adequate hydration, alkalisation of urine, and diuresis were administrated to the patients with haemoglobinuria. One patient progressed to acute kidney injury (AKI) while others had good clinical outcomes. CONCLUSION: Haemoglobinuria is a controllable side effect after MWA of liver tumours, which is related to high MWA energy, long MWA duration, and great MWA volume. It usually caused few side effects on renal function with correct treatment. (C) 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.