There is a large variety of methods to apply in improvement projects. Their various possible permutations can make it difficult for a company to choose the best approach for its project-related and organizational characteristics. Solving problems, starting with the simplest and ending with the organizational desire to become a world - class organization drives to implementation of some improvement methods which increase competitiveness and help companies to satisfy their customers. Six Sigma, 8D, PDCA (Plan-Do-Check-Act), Ishikawa (Fish Bone), 5Why - are among the most popular methods which can guide and support an organization’s improvement projects and can been selected as improvement methods.