Sir, I enjoyed reading the interesting case report of an allergic reaction to mercury and the accompanying review of the literature (BDJ 2008; 205: 373–378). The acute reaction described is fortunately very rare but as such, these types of reactions may not always be recognised when they occur. As well as the skin manifestations described, a further rare presentation not mentioned is the so-called 'baboon syndrome'.1,2 This is a syndrome of striking, bright erythema of the buttocks combined with dermatitis in flexural areas. Interestingly, acute reactions have most commonly been reported from Japan and Korea where mercury containing disinfectant has been implicated in increased rates of mercury sensitisation.2,3 Whatever the manifestation of the acute allergy, in patients who have had acute reactions to mercury, subsequent amalgam removal, if required, should be performed under rubber dam and with high volume suction to reduce exposure to released mercury.4