Background: Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and is a leading cause of cancerrelated death worldwide. It is the third most common cause of death of cancer worldwide. RFA is one of the most important modalities in treatment of HCC because it is minimally invasive, low risk of morbidity and excellent tumour control. PET/CT provides a functional and morphologic data in a single session for detecting residual of HCC after RFA. Presence of focal areas with increased FDG uptake within the ablated area is suggestive of residual disease while completely photopenic lesion after ablation is suggestive of well ablation. Aim of the Work: to emphasize the role of PET/CT in follow up of HCC after radiofrequency ablation. Patients and Methods: This prospective observational study was conducted on thirty patients, 25 men and 5 women. The Patients were referred to radio-diagnosis department, Ain Shams University hospitals, radio-diagnosis department, PET/CT unit in a period of 8 months of data collection for patients who underwent radiofrequency ablation for HCC at the interventional radiology unit. Results:The optimal cut of value of standardized uptake value ratio (SUVmax/liver SUVmean ratio) for detection of residual viable HCC after PET/CT was 1.81 with sensitivity, specificity and accuracy of 66.7%, 96.3%, 93.3% respectively. Conclusion:18F-FDG PET/CT showed high diagnostic accuracy in evaluation of the intervention bed following RFA which helps in detecting residual disease. Another super added advantage is the high capability to detect wide extrahepatic metastasis in the same examination.