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Introduction:In the last three decades, of the vascular catheters researchers are discussed, along with the many questions that so far has not been definitively answered. So, the question remains whether it can be used for sampling venous line?The aim of this study was to determine and compare the biochemical laboratory values, blood samples were taken from the peripheral vein infusion continuously receives intravenous fluid and the usual method of sampling was carried out. Methods:This study is a quasi-experimental intervention, which is controlled on 60 patients hospitalized in the internal medicine ward were selected for sampling Two samples from each patient's blood through a peripheral intravenous line (about) 5 cc of blood thrown after the first 5 ml of IV and gather other then the usual manner, the other samples (control) were prepared .Then all the samples amounts of sodium, potassium, urea and creatinin using software spss19, paired t-test and Pearson correlation analysis was. Results:The mean values of sodium, potassium, urea and creatinin group, respectively 133/60mEq/l, 4/50mEq/l, 14/57mgr/dl, 1/32mgr/dl and control groups, respectively133/37mEq/l, 4/52mEq/l, 14/68mgr/dl, 1/32mgr/dl was. No statistically significant differences between the experimental values measured in the two groups were observed. Conclusion:In order to measure the amounts of sodium, potassium, urea, creatinin blood samples taken from the peripheral vein infusion of 5 ml thrown after the first sampling, can be used.