Background:rnInternal quality control (IQC) is designed to detect, reduce, and correctrndeficiencies in a laboratory's internal analytical process prior to the release of patient results, inrnorder to improve the quality of the results reported by the laboratory. As different studiesrnindicated, 5% to 10% of laboratories are deficient in IQC practices, including IQC frequency,rnuse of appropriate material, and statistical processing. Understanding what medical laboratoryrnprofessionals know about IQC, their thinking about it and their actual practice of what they knowrnwill help to design solutions for improving quality of medical laboratory service.rnObjective: To assess Knowledge, altitude and practices (KAP) of medical laboratoryrnprofessionals on the use of IQC for laboratory tests among selected Health centers.rnMethods: Cross sectional study design was employed from December 2013 to May, 2014 tornassess KAP of IQC for laboratory tests on 175 medical laboratory professionals working in 30rnselected health centers in Addis Ababa. The data was entered and analyzed using SPSS versionrn19.0 soft ware. Descriptive statistics was computed for most of the study variables. Logisticrnregression analysis was used to determine associations with dependent and independentrnvariables; crude and adjusted odds ratios were used to see the strength of the association andrncontrol for confounderâ€Ÿs effect. P values less than 0.05 were taken as statistically significant.rnResult: From a total of 175 study participant majorities (81.7 %) had better Knowledge aboutrnpreparing in house made IQC and 18.3 % have no knowledge about it.. All in all 98 (68.5%) ofrnthe study participants did not face failed result for IQC while 45 (31.5%) had faced failed result.rnAnd their decision for failed IQC result was 21(46.6%) immediately reject whereas 24 (53.3 %)rnof them would repeat the test before rejecting the result. When study participant's feeling wasrnclassified as bad, good, very good and excellent, 4 (2.3%) had bad, 79(45.1%) had good, 38rn(21.7%) had very good and 54(30.9%) have excellent attitude towards IQC.rnAbout 32 (18.3%) of the study participants had never performed IQC while 143(81.7%) of themrndeclared that they perform IQC. However, only 49.1% had documented their IQC result and thernremaining 50.9% have no document. Regarding frequency of IQC, 64 (57.6%) of them performrnIQC per batch, 24 (21.6%) daily, 6 (5.4 %) monthly and 17(15.3%) claimed performing IQCrnweekly. And over all 53(47.8%) of the respondents accepted this frequencyrnMajor reason for not performing IQC for laboratory tests in this study were work load, difficultyrnof IQC materials to prepare for some routine tests, cost of IQC materials, lack of supply, lack ofrnstaff members. The major factors for good IQC practice in this study were educational level,rnwork experience, participation in SLMTA program. Taking LQM training, however, had nornsignificant association both with Knowledge as well as IQC practice.rnConclusion: The study demonstrates good IQC knowledge and attitude which is not translatedrninto an equivalent practice as demonstrated by poor documentation. Working in a laboratoryrnwhich participates in SLMTA has a positive association while LQM training has no significantrnassociation with IQC knowledge and practice. Hence, practice focused training as well asrnmotivation activities are needed to promote the use IQC and reduce rate of error for laboratoryrnresults