Contact dermatitis is one of the most common reasons for consultation in dermatology. However, general dermatologists do not always appreciate the importance of patch testing. These tests should ideally be performed in specialist skin allergy units, most importantly in cases suggestive of contact dermatitis, severe acute dermatitis, chronic persistent dermatitis, and dermatitis affecting the eyelids, genital region or adjacent to venous ulcers. Eczematous changes in pre-existing skin lesions or lesions at atypical sites in patients diagnosed with atopic eczema should also be investigated. Finally, cases diagnosed as occupational dermatitis can be best managed by the workers’ health insurance scheme.