A circumscribed eczematous dermatitis occurred over the site of a cardiac pacemaker implantation. The patient subsequently developed nummular eczematous lesions of the left axilla, left ankle, and hands and wrists. Possible mechanisms include: (1) primary irritant dermatitis to medical grade silicone elastomer (Silastic Medical Adhesive Silicone type A); and (2) a nummular eczema analogous to that which sometimes follows allergic contact dermatitis to nickel or chromium.