Background: Numerous global initiatives in Africa have focused on clinical laboratoryrnharmonization and standardization, and accreditation. Though accreditation has many advantagesrnand advocated largely, it is still challenging for the laboratories to fulfill all requirements and therncriteria of accrediting bodies. So identifying the different challenges faced by the laboratoriesrnduring the process of accreditation is important for proper planning and action to resolve thosernchallenges.rnObjective: To assess the major challenges of Medical Laboratories for ISO 15189 accreditation inrnselected government hospitals of Addis Ababa, Debrebrhan, and Bishoftu, Ethiopia.rnMethod: Cross sectional study design using qualitative and quantitative data collection approachrnwas used from March to May 2017. The data for this study was gathered using structuredrnquestionnaire and in-depth interview. Stratified-proportional sampling technique was used. Datarnwas entered, cleaned using EPI-Data 3.1 and exported to SPSS version 20 software for furtherrnprocessing and analysis. Simple descriptive statistics like percentages and frequency was used. Thernqualitative data from in-depth interview were categorized and discussed.rnResult: In this research 175 questionnaire respondents and 24 key informants from 12 hospitalsrnwere included to identify the major challenges facing medical laboratoryâ€™s accreditation process.rnAll respondents had awareness about the accreditation process but only 79% of them haverninvolved in the process in one or more ways. More than half of the respondents (51%) had trainingrnexperience related to either laboratory LQMS or ISO accreditation. High turnover of trained andrnexperienced laboratory professionals for better job opportunity and education was reported tornmainly affect the accreditation process. Routine work load, poor equipment quality, shortage andrnquality of laboratory supplies, inconsistent mentorship and training, strict assessment process andrnlow attention and commitment from top management were among the major challenges identified.rnConclusion: Even though there exists an effort to fulfil accreditation requirements, achieving andrnmaintaining accreditation was still challenging for many facilities due to; trained staff turnover,rntraining and mentorship inadequacy, low staff satisfaction, low quality and quantity of equipments,rnlow top management support, and poor quality laboratory facility. This study highlights the needrnfor stronger engagement, commitment and advocacy with all stakeholders to harmonize and leadrnaccreditation program effectively.rnKeywords: LQMS, accreditation, challenge, ISO 15189, SLMTA/SLIPTA, Medical laboratory