Work-related skin problems are frequent and mainly affect the hands. They can be approached by looking for indications of the 3 principal underlying types of dermatitis: irritant, allergic, or chronic. Irritation and contact allergy are closely associated: the irritation facilitates the flowering of the allergy. Skin irritation due to working conditions is often multi-causal and repetitive. Cutaneous atopy--but not that which is only respiratory or mucosal--is the main genetic risk factor for the development of a work-related skin disease. The characteristics of irritation and allergy tend to merge when the lesions become chronic. An 8-step process is suggested to establish the causal relationship between potentially damaging substances in the workplace and the resulting skin problems. In Switzerland, professional dermatitis falls under the purview of the accident insurance laws. These laws recognize causal responsibility whenever the work substances or activities are preponderant over non-professional causes.