Background. Classification of hand eczema has traditionally been based both on aetiology and clinical appearance. For 20% of cases, the aetiology is unknown. Objectives. To suggest a classification based on well-defined aetiology as well as on predefined clinical patterns and on the dynamics of hand eczema. Methods. Literature studies and discussions among members of the Danish Contact Dermatitis Group. Results. Criteria are given for the aetiological diagnoses of allergic contact dermatitis of the hands, irritant contact dermatitis of the hands, protein contact dermatitis of the hands, atopic hand eczema and aetiologically unclassifiable hand eczema. Six different clinical patterns are described and illustrated. Suggestions for general treatment principles are given. Conclusion. Operational guidelines for the diagnosis and treatment of hand eczema are described.