Arterio-venous malformations of the jaws are a very rare pathology, but can lead to fatal complications. Presented is the case of a young female patient who was referred to our hospital based on the clinical and radiological diagnosis of an odontogenic cyst related to the first molar in the right mandible. Due to a suspicious mobility of the tooth and root resorption a biopsy and tooth extraction was planned under general anaesthesia. Already during mobilisation of the tooth an enormous threatening bleeding occurred which forced in addition to surgical revision, immediate embolisation and intensive care treatment? The patient recovered well from the treatment without any long-term complications or damages. The later histo-pathological findings supported the intraoperative diagnosis of an intra-osseous haemangioma.