The acrylic content of modern dental materials poses a risk of adverse reactions. Although the quantities of the substances released are normally too small to cause systemic reactions, local reactions may occur resulting in damage to the skin. A study, in which 81 dental workers referred to dermatologists for a variety of adverse reactions were patch tested, showed work-related dermatoses to represent a serious problem for dental staff, sometimes entailing occupational disability and re-schooling. Much of this could be avoided by observing special precautions to prevent direct contact with the sensitising substances in composite materials used in dental surgery. Since the use of dental amalgam has been reduced to about 10 per cent of all fillings in Sweden, the prevalence of adverse local reactions to the acrylic composite materials which are used instead may be expected to increase.