Objective To investigate clinical characteristics and risk factors for premature atrial contractions in children, which will provide effective reference for diagnosis and evaluation of premature atrial contractions. Methods Through history collection, physical examination, echocardiogram and electrocardiogram examination, 212 children were enrolled, who were diagnosed as premature atrial contractions without organic heart diseases.All clinical data of these children were analyzed.One hundred and sixty-nine children received dynamic electrocardiogram and treadmill exercise test. Results (1) Age distribution: 28-day to 1-year old children with the rate of 10.8%(23/212 cases), 1 to 3-year old with 9.4%(20/212 cases), 4 to 6-year old with 28.8%(61/212 cases), 7 to 10-year old with 21.2%(45/212 cases) and ≥11-year old with 29.8%(63/212 cases). There were 101 boys and 111 girls, with the ratio of 1.0:1.1.(2) There were 139 children(65.6%) without any symptoms, and 73 children(34.4%) with some symptoms, which mainly included sighing, oppression in chest, weakness, breath holding, palpitation, dizzy and pale complexion.The occurrence of sighing was higher to 83.6%(61/73 cases). (3) There were 85 children(61.2%) without symptoms who were found to have premature atrial contractions by routine physical examination, and there were 54 children(38.8%) who were found to have premature atrial contractions during visiting doctors because of other diseases such as infectious diseases.Usually, there were some incentive factors, such as infection(36/54 cases), exercise(15/54 cases), mental stress(11/54 cases) and fatigue(7/54 cases), among which infection was the most common one.(4) Between healthy children and those with premature atrial contractions, there was no statistic difference in basic heart rate, blood pressure, left ventricular end systolic dimension(LVDs), left ventricular end diastolic dimension(LVDd), ejection fraction, shortening fraction, and left atrial diameter(all P>0.05). (5)Number distribution of dynamic electrocardiogram per 24 hours: 20 000 with 13.7%(29/212 cases). (6) Exercise test of 169 children: during and after exercise, there were 135 children(79.8%) with decreased or disappeared premature contractions.There were 34 children(20.2%) with increased and pleomorphism premature contractions during exercise, and junctional escape rhythm, pairing premature contractions or ST-T changes.(7) Relation between frequency of premature contraction and treadmill exercise test: positive rates of exercise test were 20.2%(17/84 cases), 20.3%(13/64 cases) and 19.0%(4/21 cases) of children with 20 000/24 hours respectively.There was no statistic significance among groups(χ2=0.017, P=0.991). (8) Relation between apex time with exercise test: there was some relationship between premature contractions and sympathetic activity.Positive rate of daytime type(102 children) and nighttime type(67 children) were 28.4%(29/102 cases)and 7.5%(5/67 cases)respectively.There was statistic significance between the 2 types (χ2=0.001, P=0.001). Conclusions Children with premature atrial contractions have marked clinical characteristics in age distribution, and most children have no obvious symptoms.Infection is the most common incentive fact.It is necessary to finish dynamic electrocardiogram to investigate the distribution of premature contractions, and to finish exercise test to evaluate the risk degree of exercise for children with premature atrial contractions. Key words: Premature atrial contraction; Characteristics; Exercise test; Child