Fluodeoxyglucose-positron emission tomography (FDG-PET) imaging is an acknowledged modality for the follow-up of solid tumours treated with thermal ablation, with persistent or new FDG uptake at the ablation site considered to be a reliable indicator of local recurrence. Several cases of proven false-positive FDG-PET scans are illustrated in this pictorial essay with uptake at the site of the ablated tumour, remote from the ablated lesion and in mediastinal and hilar lymph nodes. Positive FDG-PET scans post-thermal ablation of lung tumours therefore cannot always reliably predict local tumour recurrence or nodal spread. It is important to be familiar with FDG uptake patterns post-ablation and their significance. FDG-PET avid lesions post-ablation may require histological confirmation before further therapy is planned or management is changed.