Purpose: The aim of this study was to determine the impact level of improvements and positive contributions in clinical laboratory processes by using the six sigma protocol as quality management tool. Materials and Methods: In this study, “Six Sigma Protocol” has been applied for classification and investigation of errors and their reasons as well as evaluation of method performances of Çukurova University Medical Faculty Balcalı Hospital Central Laboratory. In order to study at universal standards, the base line status was established by analyzing the resources and frequency of the errors. As a result of detection and classification of the errors, corrective activities, beginning from the most affected processes, have been planned. Results: Six sigma levels of the preanalytical stage were found to be increased from 4,250-4,357 to 4,500-4,625. The highest six sigma level of analytical phase was 10,5 for amylase test. Sigma level of potassium turn around time was increased from 2,250 to 2,500 in the postanalytical stage. Conclusion: This study has given the opportunity for elimination of errors potentially harmful for patient health and choosing appropriate internal quality control rules. Therefore, high quality services were shown to have positive contribution to hospital budget by decreasing costs due to lack of quality, despite the costs of corrective activities and actions taken. Laboratory performances were calculated in means of universal criteria and compared with that of other clinical laboratories, as well. Sigma levels of laboratory processes which were found above 4-5 confirm that services provided by our laboratory were in accordance with international quality standards.