Patch testing is the standard procedure used to diagnose allergic contact dermatitis. It is an in vivo test, which reproduce the reaction to a contact allergen. This in vivo test aims to reproduce the elicitation phase of allergic contact dermatitis and is performed applying allergens under occlusion on the skin under standardized conditions. These guidelines for the best practice in performing patch test has been developed by an Italian group of experts taking in account the Italian legislation and local pharmacological governance. Guidelines are adapted from the original article under the guidance of the European Society of Contact Dermatitis (ESCD) and on the basis of the SIDAPA guidelines.