Background: Laboratory must have procedures regarding the reporting of the results of critical diagnostic tests because this is an essential part of the patient safety. The critical value is the result of a test that is significantly outside the normal value limit which can provide an indication of high risk or conditions that life threatening. The critital value released is must be guaranteed valid based on good laboratory quality control. Metodh : This is mix metodh with descriptive qualitative and quantitative study. The data using secondary data of daily Internal Quality Control (IQC) which was assessed using the westgard multirules and its relation to the results of critical values and interview with laboratory staffs. Result and Discussion: Daily IQC in laboratory of hemoglobin, urea, and creatinine in January-December 2017 was good, there was no westgard multirules violation. The critical value result released by laboratory are valid. However, the thema focuse based on qualitative study are 1) standart operational procedures (SOP) IQC should be detailed with westgard multirules and SOP reporting critical value result and documentation , 2) quality management system (QMS) laboratory needs to reduce errors from the pre-analytical, analytical, and postalitic phases, 3) human resourch management to improve laboratory staff skills and knowledge with continue professional development (CPD), 4) and laboratory information systems (LIS) is needed which facilitates the interpretation of IQC with westgard multirules with user-friendly application. Conclusion: Laboratory needs more detailed SOP about IQC and critical value, improve and supervision on QMS, CPD for staff, and LIS to fasilitate IQC with westgard multirules.