Background: A diagnostic error was a much wider issue in the Laborotory Medicine and further steps are required towards improving in Understanding the issue to reduce the errors in Lab. The current study about the nature of laboratory testing associated errors mainly concerns from ordering test to interpretation of results and importance in reducing errors. Objective: To study errors in 24 hrs lab of GGH Kurnool for 3 months over the whole testing cycle including pre-analytical, analytical, and post-analytical phases. Materials and methods: The number of different type of errors in Pre- analytical, analytical and post-analytical phases was recorded on designed proforma for 2 months from Oct 2021 to NOV 30 2021. All collected data was entered and analysed by using SPSS version 21. Results: Over 2 months, all venous and arterial blood samples were received in 24 hrs lab of GGH. Of the 1, 80, 011 samples received during the study period, 2340 samples were found to be unsuitable for testing, accounting for 1.30% of the rejection. All these samples were rejected due to different types of pre-analytical errors that are due to All these samples were rejected due to different types of pre-analytical errors that are due to misidentification (0.06%), incorrect tube (0.1%) missing samples (0.06%), draw from IV site (0.09%), inadequate samples (0.5%), wrong timing of sample collection (0.09%), hemolysed samples (0.3%) and lipemic samples (0.1%). Conclusions: The use of a consensually-defined list of evidence-based Quality indicators to be applied in the accreditation programs of clinical laboratories according to the current International Standard (ISO 15189:2012) is an effective tool for improving quality, decreasing the risk of errors and increasing patient safety.