A simple, reproducible and reliable method is proposed for measurement of cotyloid version. Using a standing frontal image of hip, the cotyloid borders are identified and a single-plane geometric projection determines the precise degree of version. This study can also be made from a conventional frontal pelvic image with bipodalic weight bearing. Knowledge of spatial orientation allows a better approach to head-cotyle biomechanical phenomena and thus improved understanding of the genesis of certain hip diseases.