This study evaluates the impact of the College of American Pathologists Laboratory Accreditation Program on pre-analytical errors in clinical laboratory settings. The quasi-experimental design was utilized in this study, comparing the pre analytical error rates one year before and one year after the implementation of the CAP accreditation. Data was collected from June 2021 to May 2023, amounting to 3,756,369 pre-accreditation and 4,162,673 post-accreditation tests. These pre-analytical errors were categorized and analyzed by using descriptive statistics and trend analysis. The results reflected a significant decrease in the general pre-analytical error rate from 0.0393% to 0.0252%, a reduction of 35.88% after CAP accreditation. The most impressive improvements were made in sample quantity errors (36.1%), hemolysis (32.8%), and wrong labeling (56.5%). Even with an increased number of tests conducted, the overall number of pre-analytical errors fell from 1,478 to 1,049. The reasons noted for these improvements were better training of the personnel, uniformity in operating practices, automation of systems related to sample tracking, as well as error alerting-all associated with robust quality management systems that were introduced through the process of CAP accreditation. This leads the study to the conclusion that "CAP accreditation significantly raises laboratory quality and patient safety by reducing pre analytical errors." However, a single-site focus introduces limitations regarding generalization from the current study and thus encourages multi-center studies for further verification through various settings of laboratories.