Background <p>To report the elusive presentation of a huge ovarian fibroma in a postmenopausal woman, the role of Magnetic Resonance Imaging (MRI) in its evaluation and final diagnosis, with the histopathological examination.</p> Case report <p>A 50-year-old postmenopausal woman presented with a large right ovarian tumour, ascites, and high levels of CA-125. On MRI, the lesion appeared solid to cystic, exhibiting heterogeneous, hypointense-hyperintense signal, with diffusion restriction in the solid component of the mass in diffusion-weighted magnetic resonance (MR) images. A definitive diagnosis of right ovarian fibroma was reached after the histological analysis revealed fascicles and sheets of spindle cells within a collagenized stroma.</p> Conclusion <p>This case report highlights the atypical and deceptive presentation of ovarian fibroma, emphasizing the challenges in clinical and imaging-based diagnosis.</p>