We report a case of sclerosing stromal tumor of the ovary in a 30-year-old pregnant patient presenting with pelvic pain, dysuria, and metrorrhagia. Very few reports of sclerosing stromal tumor of the ovary during pregnancy have been presented. The purpose of our work is to present the findings at physical examination, ultrasonography, magnetic resonance imaging, and histopathology, to review the literature regarding this uncommon neoplasm, and to show the usefulness of magnetic resonance imaging in the assessment of pelvic masses during pregnancy.