AbstractIn a series of 31 cases referred for the evaluation of fetal arrhythmia, it was possible to identify the rhythm disturbance correctly using M‐mode echocardiography. Cross‐sectional echocardiography delineated structural abnormality where it occurred in association with an arrhythmia. Fifteen cases had premature atrial or ventricular contractions occurring in structurally normal hearts. These were not associated with perinatal mortality or morbidity in our series. Nine cases had complete heart block, three of which had structural cardiac anomalies. Seven cases were of atrial tachycardia, six were treated prenatally, one was delivered prematurely. Correct identification of an arrhythmia and appropriate prenatal therapy where indicated, was found to prevent unnecessary operative or premature deliveries.