Ovarian fibromatosis is a rare benign nonneoplastic condition with ovarian enlargement in young women and characterized by a proliferation of collagen-producing spindle cells surrounding normal ovarian structures. We reported magnetic resonance findings of a case that the affected ovarian parenchyma with follicles was surrounded by very low intense thick fibrous tissue on T2-weighted images such as "black garland" around the ovary. The magnetic resonance findings well reflected the pathological feature of the disease and may be diagnostic.