Background/aims: Regulations for cosmetic products primarily address safety of the products that may be used by large populations of healthy consumers. Requirements for documentation of efficacy claims are only fragmentary. This synopsis aims to review and conclude a set of standards that may be acceptable to the European Community, and the cosmetic industry, as a legal standard for efficacy documentation in Europe in the future. Methods and Results: Ethical, formal, experimental, statistical and other aspects of efficacy testing are described, including validation, quality control and assurance. The importance of user relevant clinical end points, a controlled randomized trial design and evidence-based cosmetic product documentation, validation of methods, statistical power estimation and proper data handling, reporting and archiving is emphasized. The main principles of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) good clinical practice (GCP) should be followed by the cosmetics industry in a spirit of good documentation standard and scientific soundness, but full GCP is not considered mandatory in the field of cosmetics. Documentation by validated bio-instrumental methods may be acceptable, but efficacy documentation based on information about raw materials, reference to literature and laboratory experiments are only acceptable in exceptional cases. Conclusions: Principles for efficacy substantiation of cosmetic products in Europe, as described in this synopsis, are officially proposed by the Danish Ministry of Environment and Energy to the European Community as a basis for an amendment to the Cosmetics Directive or otherwise implemented as a European Community regulation.