OBJECTIVE(S): In well-appearing newborns with suspected cardiac ectopy, we sought to evaluate our practice and test whether initial electrocardiogram (ECG) findings were associated with neonatal arrhythmias (NA). STUDY DESIGN: We identified well-appearing, non-anomalous infants >34 weeks' gestation with suspected ectopy over 3.5 years. NA was defined as >/=10% premature atrial contractions (PAC), >/=5 beats of atrial tachycardia, >/=2% premature ventricular contractions (PVCs), or >/=3 beats of ventricular tachycardia. The unadjusted associations between initial ECG findings and NA are reported. RESULT: Among 126 infants with ECGs and Holters performed, NA was observed in 38 patients (30%) and was similar whether PACs were present or not on the initial ECG (33% vs. no PACs: 29%, p = 0.6). However, NAs were identified more frequently based on the presence of PVCs on the initial ECG (83% vs. 25%, p < 0.01). CONCLUSION: NAs were prevalent and both their etiologies and impact on infants warrant future study.