Background and Objectives:
Quality improvement is defined as improving process performance and maintaining improved results. Improvement methods and quality tools are two important factors of CQI projects. This study was carried out to compare various improvement methods.

Material and Methods:
 This study was conducted to compare quality improvement methods. By using Google with specific key words and names of different models, their flowcharts were developed to determine the steps for each method.
Results:
 Thirty quality improvement methods were found. These models had 4-14 steps. Five methods such as FOCUS PDCA, TQIS, IHI, JCAHO and IMADIM were invented in health system.

Conclusion:
 In accordance with staff skills and experiences, they could use short or long models. The skilled teams could use short and simple methods. The critical success factor is selecting and training only one method in entire the organization.