<p>While measurement uncertainty is a crucial component of quality assurance in many fields, its implementation in testing microbiology laboratories often faces challenges due to the lack of expertise and the inherent variability of biological systems. Clause 7.6 of the ISO/IEC 17025:2017 standard also states that a testing laboratory shall identify the contributions to measurement uncertainty and evaluate measurement uncertainty. Evaluation of measurement uncertainty in microbiology practice is quite different from that of chemistry. For example, different days comparison of a sample that contains microorganisms may pose some challenges due to the instability these microorganisms even when stored at recommended temperature. So, not all techniques that are applicable for evaluation of measurement uncertainty in a chemistry laboratory may not be suitable for use in a microbiology laboratory.</p><p>Our laboratory is a conventional testing microbiology laboratory that performs quantitative and qualitative tests. Conventional microbiological laboratory detects and/or quantifies microorganisms using culture-based methods and does not use physical, chemical, immunological or molecular principles but relies on conventional culturing methods. The aim of this article is to share the guidelines and techniques used by our laboratory in evaluating measurement uncertainty for these tests. The approach may not be suitable for modern microbiological laboratories that utilize various sophisticated equipments (e.g., polymerase chain reaction machines, sequencing machines) to detect and/or quantify microorganisms due to the differences in sample analysis techniques. As we focus on readily available resources and simplified calculation methods to evaluate measurement uncertainty, we believe that the approaches we use which focus on technical uncertainty can serve as a useful practical guide for other similar laboratories.</p>