A US study involved 10 acne experts in an Internet-based iterative Delphi survey to determine essential clinical components and features for an acne global grading scale. The process involved three iterative rounds focusing on clinical components, consensus for inclusion, clinimetric properties, ease of use, categorization and acceptance criteria. It was concluded that the ideal acne global grading scale would comprise essential clinical components of primary acne lesions, their quantity, extent and facial/extrafacial site involvement. Features of clinimetric properties, categorization, efficiency and acceptance would also be included (Tan, J. et al. J Am Acad Dermatol 2011, Advance publication).