Objective The aim of this paper is to quantify the condyle position of obstructive sleep apnea(OSA) patients using effective mandibular advancement appliances. Methods Twenty-one OSA patients, who hadbeen successfully treated with mandibular advancement appliances, were recruited for the study. The digital film imagingof the temporomandibular joint by transcranial projection was recorded bilaterally at three conditions: the intercuspidocclusion, the maximum open bite position before treatment, and the occlusion when the appliance was inplace. The anterior-posterior and vertical location of the condyle were measured from the film imaging. Paired t-testswere used to compare condyle positions among three occlusions. Correlation between the change of condyle positionand effectiveness of the oral appliance were calculated. Results The condyle positions significantly differed amongthree occlusions ( P < 0.05 ). The upper point on the condyle of the patient wearing a mandibular advancement appliancewas positioned at X(-1.21 ± 1.98) mm and Y( - 0. 68 ± 1. 08) mm. The correlation between the change ofcondyle position and the effectiveness of the oral appliance were poor ( protrusion r = 0.057, inferiorly r = 0. 024 ).Conclusion The upper most point of the condyle in the OSA patients wearing the effective mandibular advancementappliance was close to the articular tubercle point of the temporomandibular joint. Objective The aim of this paper is to quantify the condyle position of obstructive sleep apnea (OSA) patients using effective mandibular advancement appliances. Methods Twenty-one OSA patients, who hadbeen successfully treated with mandibular advancement appliances, were recruited for the study. The digital film imagingof the temporomandibular joint by transcranial projection was recorded bilaterally at three conditions: the intercuspidocclusion, the maximum open bite position before treatment, and the occlusion when the appliance was inplace. The anterior-posterior and vertical location of the condyle were measured from the film Imaging. Paired t-testswere used to compare condyle positions among three occlusions. Correlation between the change of condyle positionand effectiveness of the oral appliance were calculated. Results The condyle positions significantly differed amongthree occlusions (P <0.05). The upper point on the condyle of the patient wearing a mandibular advancement ap pliancewas positioned at X (-1.21 ± 1.98) mm and Y (-0.68 ± 1.08) mm. The correlation between the change ofcondyle position and the effectiveness of the oral appliance were poor (protrusion r = 0.057, inferiorly r = 0.024) .Conclusion The upper most point of the condyle in the OSA patients wearing the effective mandibular advancement app was close to the articular tubercle point of the temporomandibular joint.