We determined the potential benefits of apparent diffusion coefficient (ADC) values of enhancing-nonenhancing solid portions, cystic-necrotic areas and surrounding edema in the differential diagnosis of brain tumors. Eighty-eight patients with brain tumors: 16 low-grade gliomas, 21 high-grade gliomas, 26 metastases and 25 meningiomas were imaged prospectively in a 1.5 Tesla magnetic resonance (MR) unit. Routine MR imaging and echo-planar diffusion-weighted imaging (DWI) with b values of 0 and 1000 mm(2)/s were performed. ADC values were obtained in different tumor parts and peritumoral edema. The ADCs of contrast-enhancing tumor regions were higher in high-grade gliomas than meningiomas (p<0.05). No significant differences were found in ADCs of contrast-enhancing regions comparing other tumor groups (p≥0.05). The ADCs in non-enhancing tumor regions did not differ between low-grade and high-grade gliomas (p≥0.05). The ADCs in cystic-necrotic regions of tumors and surrounding edema were not significantly different comparing all tumor groups (p≥0.05). There were no significant differences between ADCs of contrast-enhancing and non-enhancing regions of high-grade and low-grade gliomas (p≥0.05). No significant differences were found in ADCs of contrast-enhancing and non-enhancing areas of tumors comparing to surrounding edema (p≥0.05). ADC was not found to be useful in distinguishing different tumor types and its value in the diagnosis of brain tumors is limited due to considerable overlaps.