Background: Method validation and verification are among the requirements to be fulfilledrnby the laboratories in order to attain quality management system and assessing their ownrncompetence. There is paucity of data in Ethiopia regarding the laboratory professionalâ€™srnknowledge, attitude and practice on method validation/verification.rnObjective: To assess the knowledge, Attitude and Practice on method validation/verificationrnand associated factors of laboratory professionals in selected health facilities in Addis Ababa,rnEthiopiarnMethods: Institutional based cross sectional study design using qualitative and quantitativerndata collection approach was applied in Addis Ababa from 01Dec 2020 to 30March, 2021 onrn400 medical laboratory professionals working in selected health facilities. Data was enteredrnand analyzed by SPSS version 23. Descriptive statistics was computed for most of the studyrnvariables. Likert scale analysis was used to analyze the attitude level and logistic regressionrnanalysis was used to determine associations with dependent and independent variables.rnFrequency distribution tables were used to describe the findings. P values less than 0.05 wasrntaken as statistically significant when looking for associations between dependent andrnindependent variables.rnResult; From a total of 400 participants, 85(21.3%)of them had better knowledge on methodrnvalidation/verification. Majority of the study participants, 397 (99.3%) had a good attitude onrnmethod validation/verification. Regarding their practice on method validation/verification,rn344(86.6%) and 324(81%) of the participants did not perform method validation and methodrnverification respectively. Majority of the respondents 326(81.5%) didnâ€™t take trainings onrnmethod validation/verification. And the associated factor that affects the implementation ofrnmethod validation/verification were 15(3.8%) due to competent staff turnover, 18(4.5%)work load, 42(10.5%) lack of training.rnConclusion; These study resulted that there is a good attitude but lower knowledge and poorrnpractice on method validation/verification. Absence of adequate training and work experiencerno the laboratory professionals are the major factors, and continues training, education andrnmotivation is needed to implement laboratory quality management system.