Bacterial brain abscess (BBA) is a focal parenchymal brain infection that can be caused by aerobic and anaerobic microorganisms. These microorganisms can be of exogenous and endogenous origin. One of these pathogens is Fusobacterium nucleatum. It can frequently cause BBA secondary to periodontitis in patients with poor oral hygiene. BBA is diagnosed by neuroimaging techniques. Clinical and radiological findings may mimic necrotic brain tumors. The differential diagnosis of brain abscess and necrotic tumors using imaging techniques is usually difficult. In this article a case of brain abscess due to Fusobacterium nucleatum is presented. We have emphasized that brain abscess and brain tumors can show clinical and/ or radiological similarities and the differential diagnosis should be done carefully.