Empirical evidence is presented from 11 case study companies, from which 43 employee interview transcripts were analyzed along with company documents. All the companies have experience of Six Sigma, but with varying levels of progress and success. The business types are varied, including manufacturers, sales and service companies and a national airline. The research questions aim to identify areas of weakness in the Six Sigma methodology that require enhancement; to determine any issues or difficulties associated with the implementation process and how they differ between manufacturing and service processes; to add to the current literature on the Critical Success Factors and to study the effect of national culture in an Asian environment. Key findings include: (i) whilst the Six Sigma phenomenon is generally perceived positively, it is concluded that Six Sigma is more appropriate for high risk, complicated, large scale and cross functional projects and cannot be cost justified for smaller projects; (ii) the Six Sigma methodology needs to be enhanced to ensure that projects are aligned to company goals as the evidence suggests that Six Sigma is less successful if it is too much geared towards shortsighted financial targets that do not have management buy-in; (iii) the evidence questions standard text book advice that a ‘Black Belt’ (BB) should have a full time role, suggesting that a part-time BB role can be a more realistic option particularly in a small company and (iv) the training materials available need to be improved to be more appropriate for service operations.