Diagnostic criteria for determining probability that contact dermatitis arose from a job related agent or was aggravated by such an agent, for coverage under workers compensation laws were presented. The criterion were: is the clinical appearance consistent with contact dermatitis; are there workplace exposures to potential cutaneous irritants or allergens; is the anatomic distribution of dermatitis consistent with the form of cutaneous exposure in relation to the job task; is the temporal relationship between exposure and onset consistent with contact dermatitis; are nonoccupational exposures excluded as likely causes; does removal from exposure result in improvement of dermatitis; and do patch tests or provocation tests implicate a specific workplace exposure. There may be cases in which a worker was hired who had a preexisting condition and later presented for compensation. Under this circumstance there were two additional criteria to consider. First, has new dermatitis occurred on skin surfaces not previously affected by preexistent dermatitis, and, second, has dermatitis become more severe on skin surfaces already affected by preexistent dermatitis although new surface areas are not involved. The author indicates that when considered individually, none of these conditions alone is enough to substantiate a claim; taken together, they form a logical basis for arriving at a conclusion.