Describes the procedure for the assessment of medical devices and their constituent materials with regard to their potential to produce irritation and skin sensitization. Includes: a) pretest considerations for irritation, including in silico and in vitro methods for dermal exposure; b) details of in vivo (irritation and sensitization) test procedures, and; c) key factors for the interpretation of the results. Instructions are given in Annex A for the preparation of materials specifically in relation to the above tests. In Annex B several special irritation tests are described for application of medical devices in areas other than skin.