Objectives: Urine specimen determinations sometimes may not be done immediately and may be studied by using urine strips which are ke pt in open air during routine work due to the conditions of study. In this study, the performance characteristics of urine strips and the changes in urine samples which were kept in open air were evaluated.

Materials and Methods: In the first step of study, 70 urine samples were analysed at 0, 2, 4, 6 th hours for the determination of changes in the samples.In the second step of study, urine strips kept in open air for 3 to 10 days were used. Urine specimens were analysed by both strips which were kept in original boxes and strips which were kept in open air.

Results: 100% false positive results were found for nitrite in urine strips kept in open air at 10th days.23% decrease in protein, 20% decrease in glucose and 33% negativity in keton measurements were observed in urine samples which were kept in open air for 6 hours. 10% decrease and 21% increase in density analysis, 23% decrease and 20% increase in pH analysis were found. Positivities were determined in nitrite analysis and bacteriuria (31%, 17% respectively) at 4 th hour in urine samples. There were 61% decrease in positivity of leukocyte at 6 th hour in specimens which were evaluated by both microscopy and strips. In the specimens which were evaluated by microscopy 75% decrease in positivity of erythrocyte was observed; however there were no changes in strip analysis.

Conclusion: In conclusion, according to these findings, it's very important to performe urine analysis in fresh urine as much as possible to achieve more reliable results. However, it was observed that accuracy in biochemistry analysis has not been affected by using urine strips stored in open air in short time intervals during intensive routine urine studies.