The authors report a rare case of a male patient who was diagnosed with breast cancer following investigations for proptosis secondary to extraocular muscle enlargement. A 65-year-old man presented with complaints of double vision and proptosis. CT scan of the orbits showed bilateral superior rectus muscle enlargement. On further investigation, the patient was detected to have a right breast mass. Biopsy of the mass showed an intermediate-grade carcinoma in situ. The patient underwent a right radical mastectomy following which his proptosis and symptoms of double vision resolved. Repeat MRI scans showed reduction in the size of the superior rectus muscle after mastectomy. Extraocular muscle enlargement has not been previously identified as a paraneoplastic effect of breast carcinoma in a male patient. Extraocular muscle enlargement can be a presenting feature of malignancies, and an appropriate systemic workup for the occult primary when all other preliminary tests are negative should be considered.