OBJECTIVE:Anti-streptolysin O (ASO) and anti-DNase B (ADB) titers are used for the diagnosis of poststreptococcal complications. Ranges of normal values of ASO and ADB titers vary, depending on age, population and different time intervals. Although many studies have been performed for determination of the ASO titer in our country, only a few studies have been conducted for specification the upper limit of normal for (ULN) ADB. In our study we aimed to determine the upper limit of normal of ADB antibody titers in children aged 5–15.METHODS:One hundred and twenty one children aged from 5–15 who were admitted to our outpatient clinic of Haydarpaşa Numune Training and Research Hospital with noninfectious reasons between November 2013 and March 2014 were included in the study. Patients who met the following criteria were included in the study; absence of streptococcal infection in the last three months in physical examination and/or no growth of group A, C, and G of beta-haemolytic streptococci in throat culture, normal ranges of ASO and C reactive protein (CRP) levels. All serum samples were analyzed collectively by nephelometric method. The upper limit of normal value for anti-DNase B has been defined by separating the upper 20% from the lower 80% of all measurements.RESULTS:Anti-DNase B antibody levels were ranged between 50–576 IU/ml and its upper limit was 219.2 IU/ml. When analyzed according to age groups, anti-DNase B antibody levels in the group aged between 5–10, ranged between 50–576 IU/ml and its upper limit was 212.2 IU/ml, anti-DNase B antibody levels in the group aged 10–15, ranged between 50–408 IU/ml and its upper limit was 231.2 IU/ml (p=0.008).CONCLUSION:Based on our results, upper normal values ADB antibody showed variations with age in our results. Therefore national reference values should be detected by more comprehensive studies.