The presentation highlights the challenges involved in deriving acceptance criteria for the cleanliness of medical devices, particularly with regard to particle contamination, for which there are increasing requirements (e.g. from the Medical Device Directive, ISO 13485, etc.). However, there is usually a lack of concrete procedures and specifications for deriving limit values for the variety of medical devices. Pharmacopoeias such as USP Chapter 788 are therefore often used, although these only apply to parenterals and do not take into account the boundary conditions specific to medical devices. In order to close this gap, the lecture presents the model developed by the Accept-Med industry association under the leadership of Fraunhofer IPA. This approach enables the precise derivation of acceptance criteria for particles, taking into account the current actual purity status of medical devices and the frequently used limit values of pharmacopoeias.