Objective: This study was done to compare Arterial values of pH , pCO2,B.E, K+ with Central venous values and to establish a correlation between arterial and central venous values of pH , pCO2, B.E, K+ in the clinical management of selected patients in the emergency department. Methods: The study population consisted of 40 critically ill patients in emergency and critical care units. Arterial and Central venous blood gas measurements of pH, pCO2 B.E, K+ were taken. Simultaneously other variables were noted Comparision of mean values of pH , pCO2, B.E , K+ between arterial and central venous was done using t –test. Results: As per the linear regression analysis arterial values of pH , pCO2 B.E, were found to be correlated significantly with central venous values (correlation coefficient r being 0.94 for pH and r =.96 for pCO2, r =.97 for B.E), while arterial and venous values of K+ were found to be poorly correlated (correlation coeffiecient,r =.375 .). Conclusion: Central venous blood gas values of pH, pCO2 B.E can be considered instead of arterial blood gas values in continuous assessment of critically ill patients. As per this study estimation of arterial values of potassium cannot be done based on venous potassium levels. Frequent arterial punctures can be avoided by recording central venous blood gas values in monitoring of critically ill patients.