We report a case of one sister and brother with mirror image myopic anisometropia. One sister and brother complained visual disturbance. The sister was 10 years 11 months old, and brother was 8 years 4 months old. Full ophthalmic examinations were performed, including slit lamp examination, intraocular pressure, keratometry, anterior chamber depth, axial length, fundus examination and the cycloplegic refraction. The cycloplegic refractive power was -15.50 dpt cyl.+4.50 dpt Ax 85° (right eye), -1.00 dpt cyl.+0.50 dpt Ax 90° (left eye) in the sister; -1.75 dpt cyl.+2.25 dpt Ax 90° (right eye), -9.50 dpt cyl.+4.00 dpt Ax 80° (left eye) in the brother. The co-occurrence of severe myopic anisometropia in a sister and brother is extremely rare. The present case suggests that severe myopic anisometropia may be related by genetic inheritance.