The aim of this study was to evaluate the significance of heart murmur in children participating in sports activities at schools’ competitions. Methods: We conducted a retrospective case-control study with a control group consisting of children matched by gender and age. The age span of children included was 8-19 years, and the medical data including the postive diagnosis of heart murmur was collected by the school medicine doctor during the regular systematic examination. Results: The study was conducted on a sample of 160 school-age children of matching age and gender: 80 children with heart murmur and 80 without murmur. Children without murmur more often had a family history of sudden cardiac death and structural heart disease before the age of 50 (39 vs 17; p=0.021). However, children with murmur had considerbly higher rate of positive personal anamnesis regarding cardio diseases (17 vs 1, p<0.001). Systolic murmur was present in 79 children (98%), and one had diastolic murmur. There was no statistically significant difference between children with or without murmur regarding the ECG findings (p=0.325). In the murmur group 83.7% of children have innocent murmurs, with a normal echocardiogram. The majority of children from both groups are allowed to participate in sports activities in school and in doctor's opinion there is no considerable statistic differance in the sport capability between participants with or without murmur (p=0,929). Conclusion: Heart murmur in school-age children is most often innocent. Careful evaluation is required, however, in most cases it does not present an obstacle to pursue sports.