Purpose: To assess the angles between craniofacial planes and the gravity horizontal plane (GHP). Materials and Methods: The plumb line was hung from the ceiling, the Fox plane (FoxP) was placed in the mouth, and 56 Angle Class I subjects were photographed in a natural head position. FoxP represents the extraoral view of the occlusal plane. Results: In frontal view, bipupilar plane (BP) and occlusal plane (FoxP) were almost parallel to GHP. In lateral view, FoxP was almost parallel to GHP, but Frankfort horizontal plane (FHP) and Camper's plane (CP) were not. FoxP and CP were not parallel. Conclusion: CP is not a reliable landmark for occlusal plane reconstruction. FHP does not represent GHP.