Thousands of healthcare workers in British Columbia are being fit tested for respirator use as a part of respiratory protection programs emanating from the SARS outbreak in 2003. The author reviews 8 claims submitted to the Workers' Compensation Board of British Columbia for adverse reactions related to denatonium benzoate fit testing. The adverse effects varied in severity. Most claims involved respiratory symptoms and 3 dermatitis or angioedema symptoms. One asthmatic required hospitalization for a severe asthmatic reaction. These cases indicate that there may be potentially significant health risks associated with denatonium benzoate-based fit testing at least for a small group of susceptible individuals. More systematic research is required.