Background: The level of arterial lactate has been a significant indicator of studied case's prognosis. Blood gas analysis's low concordance rate between AL & peripheral venous lactate makes PVL ineffective as AL alternative. Nevertheless, PVL can be a different way to forecast studied case's prognosis, & risk of arterial puncture problems with AL can be decreased if AL range may be predicted from PVL. This can be a quick & secure test technique. Aim: To assess if VL levels may replace certain ranges of AL levels, we reviewed association among VL & AL levels in same critically sick studied cases at time of initial evaluation. Venous blood gas analysis (which lowers risk of problems related to arterial puncture required for AL measurement) can be safer & quicker test for critically ill studied cases if VL values may be utilized as substitute for AL levels. Summary: The level of arterial lactate has been significant indicator of studied case's prognosis. Blood gas analysis's low concordance rate between AL & peripheral venous lactate makes PVL ineffective as AL alternative.