Objective: To acquire parameters for stereotaxis of the mandibular nerve initial point of the trigemenial ganglion (TG) and to test the accuracy of the acquired parameters for microinjection into the mandibular nerve initial point of TG in adult rats. Methods: Sprague-Dawley rats (260-270 g) were mounted onto a stereotaxic frame. The bregma was set as an anchor point and the three-dimensional parameters between the mandibular nerve initial point of the bilateral TGs and the bregma were measured in 25 rats. The accuracy of these parameters was tested using microinjection of Evans blue dye into the mandibular nerve initial point of the bilateral TGs in 30 rats and the injection sites were evaluated by dissection. Results: The three-dimensional parameters of the mandibular nerve initial point of the bilateral TGs were 3.5 ± 0.1 mm posterior and 3.6 ± 0.2 mm lateral to the bregma, and 12.0 ± 0.2 mm inferior to the skull surface. Accuracy for the microinjection of Evans blue dye into the mandibular nerve initial point of the bilateral TGs was 86.7% (52/60). Conclusion: The acquired parameters served well for stereotaxis and microinjection of reagents into the mandibular nerve initial point of TG. Keywords: trigeminal ganglion, stereotaxis, orofacial pain, microinjection, temporomandibular disorders