Patients with developmental breast abnormalities often present to the plastic surgeon at a young age. We report our experience with 4 cases of unilateral breast abnormality (3 hypoplastic and 1 tuberous) treated with a Becker permanent expander/implant. Our approach is to insert the expander/implant, expand intermittently to keep pace with growth of the other breast and remove the filling valve under local anaesthesia on maturity. The techniques and advantages of this approach are illustrated and discussed.