Abstract The laboratory accreditation system can be broadly identified as compulsory accreditation and voluntary accreditation. Compulsory accreditation is required and enforced by law, which is seen as an extension of government¡¦s public authority. The laboratory performing the test must first be certified by the relevant official institution before being allowed to provide testing services. Voluntary accreditation is industrial accreditation based on the credibility of the test results. This research hopes to study the key success factors of commercial laboratories accredited under both the compulsory and voluntary systems. The research hopes to make recommendations to commercial laboratories on the competitive strategies which will aid in the long term development of commercial laboratories. This study analyses 12 indicators, comprising of finance, market, core competencies, learning and growth, using the five-forces model, SWOT analysis and analytic hierarchy process (AHP). The weighting order of the key success factors for compulsory and voluntary commercial laboratories is identified as follows. 1. The weight ordering of key success factors for laboratory accredited under the compulsory system: 1. brand awareness, 2. creativity, 3. core competitiveness (accredited items), 4. training, 5. service quality, 6. responsiveness, 7. differentitation and diversity, 8. investment, 9. employee loyalty, 10. use of information technology, 11. government policy (redundancy cost), and 12. economies of scale (profitability). 2. The weight ordering of key success factors for laboratory accredited under the compulsory system: 1. brand awareness, 2. creativity, 3. service quality, 4. differentitation and diversity, 5. responsiveness, 6. core competitiveness (accredited items), 7. training, 8. government policy (redundancy cost), 9. economies of scale (profitability), 10. employee loyalty, and 11. use of information technology. The conclusions above are significant to the management in the following aspects. ¡EUnder the same indices, the weighting of key success factors vary according to differences in internal and external environmental conditions, market orientation and corporate market positioning ¡EBrand awareness and creativity are equally important for laboratories accredited under the compulsory and voluntary system, there top the first and second place of the list. ¡ECapability to compete in the market is much more significant in voluntarily accredited laboratories, indicating that it is more market orientated than laboratories accredited under the compulsory system.