<p>This controlled retrospective study aimed to evaluate the effects of maxillary protraction therapy on mandibular symphysis morphology. In this regard, 35 growing individuals with skeletal class III malocclusion due to maxillary retrognathia were assigned to two groups. The experimental group (<i>n</i> = 20) was treated with a Petit-type face mask (FM), while the control group (<i>n</i> = 15) had similar characteristics and were untreated. Linear and angular measurements related to the mandibular symphysis were evaluated on lateral cephalometric radiographs obtained before treatment (T0) and after treatment (T1). Kolmogorov–Smirnov tests, paired T-tests, and independent-samples T-tests were used for statistical analyses. In the FM group, there were significant increases in the lingual height (<i>p</i> = 0.021), B–Pogonion (<i>p</i> = 0.016), and Infradentale–Menton (Id–Me; <i>p</i> = 0.003) parameters following treatment, whereas a significant decrease was found in the incisor mandibular plane angle (IMPA) angle (<i>p</i> = 0.001). In the control group, there were no significant changes in either linear or angular measurements (<i>p</i> &gt; 0.05). Intergroup comparison of treatment and observation-related changes revealed significant differences in the IMPA (<i>p</i> = 0.023) and Id–Me measurements (<i>p</i> = 0.048). The absence of significant differences in parameters other than the Id–Me-which could be related to the retrusive effect of the face mask on the lower incisors-suggests that face mask treatment does not have a significant short-term effect on mandibular symphysis morphology.</p>