Background: In laboratory medicine, the preanalytical phase is crucial. It includes the time that passes between the sample being ready for analysis and the clinician giving the order for the test. Every one of the three stages of the testing process has errors that need to be found and fixed. Materials and Procedures: The investigation was carried out at the Department of Biochemistry, Index Medical College, Indore, Madhya Pradesh, India. The study incorporated all of the preanalytical errors that were made when estimating IL-6 and procalcitonin. Using Beckman immuno assay kits, the Beckman Coulter Access 2 was used to estimate PCT and IL-6. Findings and Result: Nine preanalytical mistakes were found in our investigation while estimating IL-6 and procalcitonin. Early serum separation from the clotted sample is necessary to prevent cell-released cytokines from leaking into the serum and potentially producing false-positive results. Conclusion: Pre-analytical errors affect overall error and, in turn, the precision of the diagnosis. Repetition of training for lab technicians and ward staff nurses can lower the percentage of preanalytical mistakes.