The effects of orthodontic treatment on the facial profile, with or without the extraction of teeth, have greatly concerned orthodontists. A study was made of 80 patients with Angle Class I malocclusion. Forty patients (24 girls, 16 boys) did not undergo extraction of teeth, and 40 patients (23 girls, 17 boys) underwent extraction of maxillary and mandibular first premolars. Data were obtained from the corresponding lateral radiographs of the head taken before and after orthodontic treatment. The purpose of this study was to compare the response of the soft tissue of the facial profile in Class I malocclusions treated with and without the extraction of the 4 first premolars. The main soft tissue differences between the groups at the end of treatment were more retruded upper and lower lips in the extraction patients.