Methyl methacrylate (MMA), a monomer of acrylic resin, has a wide variety of dental, medical and industrial applications. Concerns have been raised regarding its potential toxicity in dental use, both for the patient and also in the workplace. Dental patients are also exposed to MMA leached from some dental appliances and the effects, at least in vitro, appear toxic to cells and may cause local mucosal irritation or even an allergic reaction. When exposed to MMA in the dental clinic, dentists and other dental staff appear to occasionally suffer hypersensitivity, asthmatic reactions, local neurological symptoms, irritant and local dermatological reactions. The integrity of latex gloves may also be compromised after exposure to MMA during dental procedures. MMA is not thought to be carcinogenic to humans under normal conditions of use. Techniques should be employed to reduce patients' exposure to MMA during dental procedures in order to reduce the risks of possible complications. Dental staff should avoid direct contact with MMA and room ventilation should be optimised.