A32-year-old woman presented with a symptoms of eczematous skin lesion on exposed area of hands, arms and face for several weeks. She was suffering with symptoms of her rash and itching sensation on the lesion. The patient was diagnosed as allergic rhinitis sensitized to house dust mite, but the symptoms were not bothersome. She had a previous history of drug allergy to non-steroid anti-inflammatory drugs. She was a nurse working in general ward of a tertiary hospital. Her symptoms had developed since she started working in the ward, mixing NAC and various antibiotics with normal saline. Serum total IgE level was not increased (69KU/L) and skin prick test revealed sensitization to various inhalant allergens including house dust mites. Serum specific IgE and skin prick test to antibiotics were negative. Intradermal test with NAC at 1mg/ml and 10mg/ml showed a positive result, both immediate and late reactions (after 48hours). Patch test using NAC also revealed a positive result after 96 hours. Serum specific IgE, IgG1 and IgG4 to NAC-human albumin conjugate were not detected by enzyme-linked immunosorbent assay. We report a case of allergic contact dermatitis due to NAC which was exposed in the workplace.