In this modern era of technology, there is plethora of investigations available in the market, but without deriving clinical diagnosis, indiscriminate use of laboratory investigations is expensive & misguiding. Laboratory investigations are neither shortcut nor final answer to the diagnosis. Laboratory investigations should be planned after clinical diagnosis, derived from history & clinical examination. The clinician should also know the sensitivity, specificity & reliability of the test. All these merits of the test depend upon the accuracy of the test. The accuracy of any laboratory investigation depends upon several factors like collection of sample at appropriate time, collection of specimen in specific container, storage & transportation of sample, technique used for testing etc. The clinician should keep the possible laboratory errors in mind while interpreting the laboratory investigations.