Mathias proposed 7 criteria for establishing occupational causation and aggravation of contact dermatitis (Mathias, J Am Acad Dermatol 1989, 20, 842–848). 4 of the 7 criteria must be positive to conclude occupational dermatitis. In order to evaluate the validity of these criteria, we re-examined 19 patients (17 male and 2 female) with contact dermatitis, who had given a positive answer to at least 4 of the criteria and had either exchanged their workplace or stopped working. We re-evaluated them, 2–5 years later, for the presence of contact dermatitis. 14 of 19 patients (74%) reported that their dermatitis had cleared after they had left their previous workplace. Only 5 patients still suffered from dermatitis, 2–5 years later. 3 of these 5 patients could have been exposed to the causative allergens in their new workplace. We conclude that the Mathias criteria are useful to assess occupational contact dermatitis.