Purpose: It is critical to detect the errors in the preanalytical phases and reject the unsuitable samples for the patient safety and treatments. In this study, it is aimed to determine the situations where the samples’ reasons of rejectionare needed to be examined, developed and fixed by executing preanalytical error analyzes on the samples which arrives to and gets rejected in the biochemistry laboratory from the hospital’s services and polyclinics.

Material and Methods: This retrospective study is based on the data of the samples that are received during 2019, in the biochemistry laboratory from Karaman Training and Research Hospital’s services and polyclinics. All data is received from the Laboratory Information Management System. The samples are analyzed according to their reason of rejection, laboratory unit and the departments they come from.

Results: 436.249 samples were received by the laboratory which 3.902 of them were rejected as a result of the preanalytical errors. The total preanalytical error (sample rejection) rate was calculated as 0,89% (When the “blood gasses” from laboratory units are not considered, the preanalytical error rate becomes 0,73% for the other units). When the rejection rates within the biochemistry laboratory units are examined; it is seen that sample rejections are done by the rates of 0,75% in Biochemistry, 0,39% in Hormone, 1,77% in Coagulation, 8,08% in Blood gasses and 0,55% in Automated urinalysis. The most seen reasons of rejection are respectively hemolyzed samples (43,7%), coagulated samples (23,3%) and not having correct amounts of samples (22,8%).

Conclusion: Hemolysis, coagulum and unsuitableness of the sample amounts are the most seen ones of the preanalytical errors in the Laboratory. It is important for all the personnel who are commissioned in the Total Test Process to avoid these errors. Because even though the rejection rates connected to unsuitable sample and identification errors are fairly low, they might risk the patient safety. Increasing the frequency of trainings and giving applied courses can also contribute on decreasing the preanalytical error rates more.