Abstract: Background: All coagulation tests critically depend on the quality of the plasma specimens obtained. Pre-analytical variability is a common source of errors in coagulation testing, as clotting assays are susceptible to poor standardization of the whole analytical process. Many misleading results in blood coagulation arise not from errors in testing but from carelessness in the pre-analytical phase. Pre-analytical factors influencing the reliability of laboratory testing are commonplace. Control is critical, since this has a direct influence on the quality of results and their clinical reliability. Internal Quality control should be maintained while performing the tests in the laboratory.