Molecular methods have been applied in diagnostic laboratories more than two decades. These tests are enabled to respond lots of unanswered questions and replying to many difficulties. Hence several researches have been carried on this field and many companies have specified huge investments for   requests. Despite of this efforts sensitivity and specificity still have an important situation in designing in diagnostic protocols. Standardization and reproducibility of each test have not been documented such this up to now. But we are still facing with numerous negative results that are not satisfactory for the clinicians. The aim of this survey is to look at the role of controls and causes of subject at the final results of the diagnostic tests.