A study was made on 27 cases where enucleation of four first premolars was performed simultaneously without introduction of mechanical devices to influence space closure. The results suggested that: 1. Enucleation of premolars can be used to minimize the severity of crowding in arch-length deficiency cases. 2. There is no damage to the remaining teeth and alveolar process when enucleation is accomplished with good surgical technique. 3. The average amount of lingual tipping of the mandibular incisors in approximately four years subsequent to the enucleation procedure was 4.1 degrees. 4. This amount of lingual tipping compares quite favorably with the amount of lower incisor uprighting experienced during growth and could not be considered excessive. 5. The mandible does tend to rotate in a counterclockwise manner following enucleation of four first premolars without appliance therapy. This rotation was considered significant in comparison with the amount of rotation that could be expected from an untreated sample. 6. If orthodontic treatment is planned, the enucleation of the manddibular second premolars in borderline extraction cases to avoid excessive lingual tipping of the mandibular incisors would seem to be questionable. 7. Various combinations of enucleation and tooth extraction may be helpful in treatment planning. 8. With judicious timing the enucleation of four first premolars can minimize the severity of the malocclusion simplifying appliance therapy if proper diagnosis and good surgical technique are employed. 9. Although conventional serial extraction may accomplish similar ends, it would appear that enucleation would offer some advantages in terms of autonomous adjustment of the mandibular incisors and root positioning of mandibular cuspids. 10. Enucleation cases usually require fewer traumatic surgical procedures and less supervision by the orthodontist. 11. The parents should be informed that serial extraction procedures including enucleation may simplify but will not eliminate the need for appliance therapy.