Background. According to EU legislation, 26 fragrance substance allergens must be labelled on cosmetic products. For 12 of them, the optimal patch test concentration/dose has not been evaluated. Objectives. To establish the optimal patch test doses in mg/cm(2) for the 12 fragrance substances that are not included in fragrance mix I or II in the European baseline patch test series. Materials and Methods. Patch testing with the 12 fragrance substances was performed in a stepwise manner encompassing up to five rounds in at least 100 dermatitis patients for each round. Before patch testing, an individual maximum concentration/dose was determined for each fragrance substance. Results. The predetermined maximum patch test concentrations/doses could be tested for all 12 fragrance substances, with no observable adverse reactions being noted. Conclusions. For each fragrance substance investigated, it is recommended that half of the maximum patch test dose (mg/cm(2) ) be used for aimed and screening patch testing.