Objective: The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) on condylar growth with a mandibular advancement appliance in rats. Background data: Researchers studied new methods such as laser, for mandibular condyle growth stimulation and acceleration with or without functional appliances in experimental animals, but the specific mechanism and laser energy density values for condylar biostimulation and bone cell activities are still unknown. Methods: Forty-eight 8-week-old male Wistar albino rats weighing between 260 and 280 g were randomly divided into four groups. Group I was the control group; group II was the mandibular advancement appliance group; group III was the 8 J/cm(2) (0.25 W, 20 sec) laser irradiation with mandibular advancement appliance group; and group IV was the 10 J/cm(2) (0.25 W, 25 sec) laser irradiation with mandibular advancement appliance group. Experimental rats in groups III and IV were stimulated with a low-level laser in the temporomandibular joint region bilaterally 15 times over 30 days. Morphological changes in the mandible were evaluated with lateral radiographs before and after the study with selected linear and angular measurements. Pearson correlation test, Friedman, Kruskal-Wallis, and Mann-Whitney U tests were used for statistical analysis. Results: According the lateral radiograph results, the growth of mandibles in the experimental groups was significantly more than that of the control group (p<0.05). Group III also showed greater mandibular growth than the other groups (p<0.05). Conclusions: We concluded that an intraoral appliance with LLLT, including chosen parameters, can stimulate condylar growth and increase mandibular advancement.