Skin conditions such as acne, urticaria, psoriasis, and particularly eczema (dermatitis) may have many causes. However, a work-related aetiology is often forgotten. Hand eczema is the most common occupational dermatosis. Exposure to skin irritants is the main cause with wet work playing a major role. The cause cannot be inferred from the clinical picture and it is almost impossible to distinguish between irritant and allergic contact dermatitis. Besides observation and history-taking, epicutaneous contact allergological (patch) testing is necessary for this. In occupational dermatoses, patch testing using the European Standard Series alone is often inadequate for diagnosing. Everyone with hand eczema in a risk profession is eligible for patch testing. The prognosis of hand eczema is poor: in 60% of patients the eczema becomes chronic. Genetic predisposition, such as atopic dermatitis, is seriously underestimated. This is the main risk factor for irritant contact dermatitis and, indirectly, for allergic contact dermatitis. This predisposition should give direction to career choices in young people.