Background: Quality laboratory services and systems constitute the foundation forrnstrengthening health care systems. Including Ethiopia, developing countries are on the way ofrnestablishing laboratory standards that are affordable and easy to implement and monitor in theirrnfacilities. This study was conducted to assess the laboratory starting from implementation ofrnQuality Management System (IQMS), up to the final assessment.rnObjective: The Objectives of the study is to assess implementation of quality managementrnsystem and associated challenges in Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia.rnMethod: Exploratory study was done by using available information, assessment data,rnquestionnaire, in-depth interview and observational assessment from February 14/2013 â€“ Mayrn5/2014. All willing laboratory staffs were included in the research and non-probability purposivernsampling technique was applied. Statistical analysis was carried out by using SPSS version 20.rnResult: The progress of quality management system implementation after one year and threernmonth from baseline assessment result of 41/250(16.4%) to final assessment resultrn95/250(38.0%) were 54(21.6%) with the mean value of 7.9 for12 QSE (P = 0.001).The identifiedrnchallenges were staff Job dissatisfaction leads to staff demotivation, shortage of supportivernstaffs, lack of proper laboratory management, lack of Hospital management commitment,rnweakness of supporting (management) departments finance, purchasing, budget and maintenancerndepartments, lack of budgets allocation for the laboratory, delay on purchasing system arerncritical challenges affecting the laboratory. Weakness in pharmacy supply chain managementrnsystem, very poor store management, lack of mini store, lack of backup equipment and lack ofrnequipment maintenance system are other challenging issues of laboratory. In appropriateness ofrnsample collection area benches and sinks to keep samples and documents