A narrow anterior apical base in both jaws can cause pronounced crowding, which can be corrected by extraction therapy (as a rule extraction of four premolars) or by transverse distraction osteogenesis therapy (as a rule bimaxillary), followed by orthodontic treatment. A case is reported of bimaxillary transverse distraction osteogenesis in an eleven-year old female patient. Alignment was performed with fixed orthodontic appliances. Correction of the skeletal Class II relationship was done with a functional appliance. The active treatment time was eighteen months.