Latar Belakang: Inferior Alveolar Nerve Block (IANB) merupakan prosedur paling umum dalam praktik kedokteran gigi, dan menjadi salah satu insiden kegagalan tertinggi dibanding teknik anestesi lain hingga 15-20%. Salah satu penyebab umum terjadinya kegagalan blok IANB karena tidak tepatnya dalam menentukan letak foramen mandibula. Letak foramen mandibula memiliki tiga kategori, yaitu di atas garis oklusal, segaris oklusal, dan di bawah garis oklusal. Variasi letak foramen mandibula tersebut dipengaruhi oleh faktor ras dan jenis kelamin. Mengetahui letak dan rerata jarak foramen mandibula yang tepat diperlukan untuk menghindari terjadinya kegagalan anestesi sebelum tindaklanjut tindakan medis. Tujuan: mengetahui kategori letak dan membandingkan rerata jarak foramen mandibula pada kelompok pria dan wanita usia 18-35 tahun di RSKGM FKG UI. Metode: Studi dilakukan pada 200 radiograf panoramik digital yang dibagi menjadi kelompok pria dan wanita berusia 18-35 tahun di RSKGM FKG UI. Dilakukan dengan membuat garis bidang oklusal sejajar horizontal pada distolingual cusp molar 1 atau molar 2 di kedua sisi rahang, lalu tarik garis pada bagian superior anterior kanal mandibula tegak lurus ke garis oklusal dan anterior ramus. Kemudian dilakukan uji reliabilitas intraobserver dan interobserver dengan uji ICC dan uji komparatif independent t-test. Hasil: Diperoleh rerata jarak foramen mandibula terhadap garis bidang oklusal pada kelompok pria (15,49  3,29) dan pada wanita (14,68  3,07). Rerata jarak foramen mandibula terhadap anterior ramus pada kelompok pria (14,61  3,29) dan pada wanita (13,63  3,07). Kesimpulan: Terdapat perbedaan signifikan rerata jarak foramen mandibula terhadap anterior ramus, tetapi tidak terdapat perbedaan rerata jarak foramen mandibula terhadap garis bidang oklusal pada pria usia 18-25 tahun dan wanita usia 18-35 tahun di RSKGM FKG UI.Background: Inferior Alveolar Nerve Block (IANB) is the most common procedure in dental practice, and has become one of the highest failures compared to other anesthetic techniques up to 15-20%. One of the the common causes of the failure in IANB Block is due to the inaccuracy in determining the location of mandible foramen. There are 3 categories of the location of mandible foramen - above the oclusal line, in line with the oclusal, below the oclusal line. The variety of the mandible foramen location is affected by races and gender. To acknowledge the accurate location and the average distance of mandible foramen is necessary in order to avoid the failure of anesthesia before undergoing the later medical treatment. Aim: To acknowledge the category of the location and to compare the average of the distance of mandible foramen on male and female patients aged 18-35 in RSKGM FKG UI. Methode: The study or research is carried out on 200 Digital Panoramic Radiography divided into male group of aged 18-35 and female group of aged 18-35. The measurement is conducted by drawing the lines of oclusal horizontally in line on distolingual cusp first molar or second molar in both sides of jaw, then drawing the line on anterior superior of mandible canal perpendicular line to oclusal line and ramus anterior. Finally, intraobserver and interobserver reliability tests by ICC test and t-test independent comparative are applied. Result: The average distance of mandible to the occlusal plane on male group is (15,49  3,29), on female group is (14,68  3,07). The average distance of mandibule to the ramus anterior on male group is (14,61  3,29), on female group is (13,63  3,07). Conclusion : There is significant distinction on the distance of mandible foramen to the ramus anterior, but there is no difference on the distance of mandibular foramen to the occlusal plane between male aged 18-35 and on female aged 18-35 in RSKGM FKG UI.