Radiofrequency ablation (RFA) of colorectal liver metastases is a well tolerated minimally invasive procedure. Various complications can occur but most of these are self-limiting if diagnosed and treated in time. This case report describes a serious and rare complication following RFA treatment: hepato-pericardial fistula caused by several RFA procedures aiming to cure colorectal liver metastases. Complications to RFA treatment vary and can be difficult to diagnose. We recommend that RFA procedures and management of complications take place in highly specialised multidisciplinary departments.