BACKGROUND: Recently, there are so many newly developed equipments to detect blood gas analysis with serum electrolytes. And then, so many important parameters are quickly reported from laboratory department. So, many clinicians use the data to manage the critical patient. We attempted to detemine the correlation coefficient and adjustment equation. METHODS: Total 68 patients results of Na, K that are cheked using arterial whole blood(288 blood gas system) and venous serum electrolytes analyzer(NOVA 6) were evaluated and we detemined the coefficient of two methods from April to September, 1995. RESULTS: The correlations between the results obtained with NOVA 6 and that of 288 blood gas system were excellent for both Sodium and potassium(r>0.95, p<0.001 in both). In this study, we make the regression equation to adjust the differences between the two methods. Na : y=1.004190X+7.656643(r=0.9637, p<0.001) y=venous serum Na, x=arterial whole blood Na K: y=0.994831X+0.489631(r=0.9545, p<0.001) y=venous serum K, x=arterial whole blood K. CONCLUSIONS: Specimen(whole blood, serum), kind and content of heparin also affect the results of electrolytes. And then, the report of the result after adjustment of them using above equation will provide reinforcement of the efficacy of the results using arterial whole blood specmen. We recommend it especially for emergency laboratories for critical test.