Objective: The purpose of this study was to determine whether diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) can be used to distinguish brain abscesses from cystic or necrotic brain tumors, which are difficult to distinguish by conventional magnetic resonance imaging (MRI) techniques. Marerials and methods: 19 patients with brain abscesses and 22 patients with cystic or necrotic brain were enrolled in this study.