BACKGROUND: WHO recommends that each laboratory should establish turnaround time (TAT) to monitor and evaluate performance throughout processes. The status of established TAT was not yet assessed in Ethiopian Armed Force Comprehensive Specialized Hospital. The aim of this study was to evaluate the laboratory performance and associated factors towards achieving TAT in clinical chemistry and hematology tests at Armed Force Comprehensive Specialized Hospital, Addis Ababa, Ethiopia.METHODS: Hospital-based cross-sectional study was conducted from April 2019 to June 2019. Standardized questionnaire was designed to collected data on awareness of laboratory staffs about TAT. The data was entered, cleaned and analyzed using SPSS version 24.0 Software. Logistic regression analysis was done to find out statistically significant association and strength of association between dependent and independent variables at pvalue <0.05.RESULT: A total of 422 test results were systematically selected with 100% response rates. Of these, 253(59.9%) were chemistry tests. From the expected < 90min TAT clinical chemistry tests, only 41(16.2%) and from < 60min TAT time for hematology tests, 37(21.9%) met the target. The laboratory TAT was affected by factors including high work load, laboratory information system problem, power interruption and sample collection time. Moreover, the level of knowledge, attitude and practices of laboratory staffs towards laboratory TAT were 60%, 85.7% and62.9% respectively.CONCLUSION: Overall achievement of clinical Chemistry and hematology tests TAT was poor. The finding might reflect other public hospital situation in Addis Ababa. Thus, additional large scale studies need to conduct.