Incorrect venous blood specimen collection (VBSC) practices might influence results from blood analyses and thus jeopardize patient safety. A large amount (60–80%) of important decisions in diagnosis, administration and medication are based on laboratory test results, therefore correct VBSC is of most importance. A harmonization of VBSC can lead to accurate collection procedures, rapid and correct diagnosis, and treatment. Correct test results contribute to increased patient safety and enhanced healthcare economy. VBSC errors might be consequences of both human mistakes and cultural factors in relation to the overall system. Variations in the system influencing VBSC practices might originate from international and national structures, local organizational and work cultures, and humans working in the frontline. In order to succeed in reducing sources of errors, it is of utmost importance that leaders and managers take the whole system into consideration when planning interventions in their mission to enhance practice. Thus, the aim of this article was to discuss variation in VBSC practices and how the variation might be a source of VBSC errors.