Background: Inadequate samples make laboratory tests delay cause errors, which will deteriorate the quality of the tests. Therefore, adequate samples are essential for reliable test result. To reduce the inadequate samples, they should to analyze problems and seek a way of improvement through CQI (Continuous Quality Improvement) activity. This will minimize errors during the test and produce a fast and accurate result. Eventrally, the qualily of entire test may be improved, and as a result, a good quality of medical care service may be provided. Methods: At first, inappropriate testing items were collected. Then, generating fctors and problems were investigated and analyzed in each case, In addition, the category with higher frequency wes primarily supervised. In consegalnce, a reduction of are dustion of improper testing sample was oxpected through continuous education and CQI activity. Conclusion : At the beginning of CQI activitv, the number of inadequate testing sample was of 8,591 total samples, which gives the frequency of 0.72%. As CQI activity was carried out the number of improper testing sample reduced to 58 out of 11,415 cases, which yields the frequency of 0,51%. One may notice the difference 0.2%. Among the inadequate sample(blood), there was a high frequency of hemolysis; thus, more of CQI activity is required for this specific matter. Because the occurrence of inadequate testing affects the clinical outcomes, it is extremely important that one manages each step of the procedure in collecting samples and mamtaines the quality of entire tests.