Background: Ovarian masses present a special diagnostic challenge when imaging findings cannot be categorized into benign or malignant pathology. Ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) are currently used to evaluate ovarian tumors.Functional imaging by means of diffusion weighted magnetic resonance imaging (DW-MRI) is now part of the standard imaging protocols for evaluation of the female pelvis. DW-MRI is important MR imaging technique which enable the radiologist to move from morphological to functional assessment of diseases of the female pelvis. Aim of the Study: The aim of the current study is to evaluate the diffusion-weighted MR imaging in prediction of the nature of suspicious ovarian masses which are detected previously by conventional ultrasound. Patients and Methods: MRI Unit, radiodiagnosis department, Ain Shams University hospital. The study is prospective, included thirty women who presented with suspicious adnexal masses on previous ultrasound examination and referred for further assessment and characterization by DW-MRI. Patients with contraindications to MRI (e.g. claustrophobia, cardiac prosthesis and metallic plates) are excluded. Results: The study included 30 women ranging in age between 24 and 61 years with mean age 43.22±11.15. Out of 30 cases, 12 had of benign ovarian tumors while 18 had malignant tumors. Conclusion: Thus, combination of DWI and conventional MRI implies using a completely noninvasive technique with no radiation exposure. It is cost effective (no additional cost to MRI examination), and easily added to the MR study protocols with no marked lengthening of examination time. It improves the specificity of MRI and thus increasing radiologist's confidence in image interpretation which will finally reflect on patient's outcome and prognosis.