The thesis is focused on the application of the concept of Six Sigma in the selected business process. An essential contribution Six Sigma process improvement is seen. The main tool Six Sigma DMAIC process, we chose. Using the different phases of the process we diagnosed a critical process, the error in this process and ultimately the product involved is a critical error in the technology of casting aluminum cylinder heads in the company Nemak Slovakia Ltd. Obtaining basic information on production status, we define the key measures for their subsequent implementation led to improved indicators of critical product and process errors. Improving indicators of capability for assistance methods Six Sigma, we finally quantify the potential savings, the main objective was to reduce the overall costs of the company.