SummaryBackgroundThe multifaceted clinical laboratory process is divided in three essential phases: the preanalytical, analytical and postanalytical phase. Problems emerging from the preanalytical phase are responsible for more than 60% of laboratory errors. This report is aimed at highlighting and discussing nonconformity (e.g., nonstandardized procedures) in primary blood tube mixing immediately after blood collection by venipuncture with evacuated tube systems.MethodsFrom January 2015 to December 2015, fifty different laboratory quality managers from Brazil were contacted to request their internal audit reports on nonconformity regarding primary blood tube mixing immediately after blood collection by venipuncture performed using evacuated tube systems.Results and ConclusionsA minority of internal audits (i.e., 4%) concluded that evacuated blood tubes were not accurately mixed after collection, whereas more than half of them reported that evacuated blood tubes were vigorously mixed immediately after collection, thus magnifying the risk of producing spurious hemolysis. Despite the vast ma jority of centers declaring that evacuated blood tubes were mixed gently and carefully, the overall number of inversions was found to be different from that recommended by the manufacturer. Since the turbulence generated by the standard vacuum pressure inside the primary evacuated tubes seems to be sufficient for providing solubilization, mixing and stabilization between additives and blood during venipuncture, avoidance of primary tube mixing probably does not introduce a major bias in tests results and may not be considered a nonconformity during audits for accreditation.