The study aimed to detect the incidence of arrhythmias in children with rheumatic mitral regurge. It was conducted on 30 cases of rheumatic mitral regurge and 30 age and sex matched control group. Sinus tachycardia was present in 33% of the cases, premature atrial contractions in 7%. Incidence of arrhythmias in cases of moderate and sever MR were statically significantly in cases of moderate and sever MR than control (P value .02 & 0.009 respectively). Holter monitoring detected arrhythmias statically significantly more than 12 leads ECG (P value 0.02)