Dermatitis is any inflammation characterized by the classical signs of redness, swelling, heat and pain. It is a non-specific reaction of the skin to an irritant and cannot be considered an entity. Occupational dermatitis is such a reaction produced by, or aggravated by, an irritant encountered during the course of employment. At the present time the word dermatitis is almost synonymous with occupational skin disease and the word has unfortunately become of more legal than medical significance. In view of the diversity of industrial processes and the wide range of substances which will produce irritation of the skin in certain people with average skins, it is not surprising that, with few exceptions, the eruption is not characteristic. Pain is not usually a dominant feature and is more commonly replaced by itching. The onset is occasionally sudden, but more often insidious. The appearance of the skin eruption is proportional to the severity of the reaction produced by the causative agent and the stage at which the eruption is seen. These two factors are more important than the nature of the causative agent in considering the appearance cf the eruption, although some agents produce a constant and characteristic lesion. The usual sequence of events is erythema, oedema, papules, vesicles, or more rarely bullae which on rupture exude serum. The serum dries and produces crusts. When oedema of the prickle cells occurs the granular and horny layers are imperfectly formed and adhere together to produce scales. The appearance of the