Background: Clinical laboratory errors could be classified as pre analytical, analytical and postrnanalytical. The majority of laboratory errors emerge from the manually intensive activities of thernpre analytical phase, mainly those related to collection, handling, transportation, preparation andrnstorage of diagnostic specimens. rnObjective: The main aim of this study was to assess the specimen rejection rate and associatedrnfactors among the referred specimens through referral network to Debre Markos referral hospitalrnfor laboratory testing. rnMethod: Retrospective study was conducted at Debre Markos referral hospital laboratory fromrnJanuary 2016 to December 2019 to evaluate trends of specimen rejection rate. In addition,rnprospective cross sectional study design was applied from January 2020 to April 2020 torninvestigate further associated factors of specimen rejection. Data was collected from specimenrnreception log book and from referring facilities using developed checklist. Finally, statisticalrnanalysis was done with excel 2007 and SPSS version 20.0 software. rnResult: From the total of 35673 specimens submitted to Debre Markos referral hospitalrnlaboratory from January 2016 to December 2019, a total of 560 (1.57%) specimens werernrejected. The specimen rejection rates in each year were 2.30%, 1.59%, 1.42% and 1.26 %rnrespectively from 2016 to 2019. Moreover, of 2750 specimens submitted to the laboratory duringrnJanuary 2020 to April 2020, a total of 37 (1.34%) specimens were rejected. Specimen collectorrntraining status and experience had significant association with specimen rejection rate (P= 0.01& rnP=0.04 respectively). rnConclusion: Although specimen rejection rate among referred specimens was improvedrngradually from 2016 to 2019, still needs more interventions to meet the established targetrnspecimen rejection rate (0.3%).Hence, training of health professionals on specimen collection,rnhandling and transportation of requested tests, appropriate preventive and corrective actionsrncould improve the problem in specimen referral network.