A health impact assessment (HIA) was conducted to identify potential health impacts arising from policy reform of occupational health and safety at S-chemical company, a multinational global company that employs about 13,000 workers. A multidisciplinary team of health professionals including occupational physicians, an epidemiologist, and public health researchers oversaw the HIA. A project manager from S-company was also involved in the whole HIA process. A literature review, profiling using annual health examination data and interviews with stakeholders and key informants were undertaken in order to identify possible impacts. A range of positive and negative health impacts were identified and develop recommendations for implementation of the new occupational health policy were proposed. The HIA added value to the planning process for the occupational health policy reform.