Fetal arrhythmia disorders are diagnosed in 1–2% of pregnancies during a routine ultrasound examination. In more than 90% of cases, arrhythmias are short-term and isolated phenomena that do not have much clinical significance. However, persistent fetal arrhythmias can cause the development of heart failure or fetal dropsy and even lead to fetal death. Malignant types of arrhythmias, such as supraventricular tachycardia, atrial flutter, complete atrioventricular block are the causes of intrauterine death, according to various authors, in 3-30% of cases. For such cardiac arrhythmias prenatal diagnosis with the possibility of prenatal, perinatal and neonatal intervention can be crucial and ultimately significantly improves the outcome. A. Öhman, E. Jaeggi classify fetal arrhythmias into three types: ectopic beats, tachyarrhythmias and bradiarrhythmias. Fetal tachycardia is defined as the heart rate (HR) above 180 beats per minute. It is called stable if arrhythmia is present for more than 50% of the study time, or intermittent when periods of normal heart rate and periods of tachycardia alternate. Tachyarrhythmias by localization of the rhythm driver are divided into sinus tachycardia, supraventricular tachycardia, ventricular tachycardia. The effectiveness of transplacental treatment of arrhythmia in the fetus depends on the accuracy of determining the type of arrhythmia. The correct diagnosis of the type of tachyarrhythmia is crucial for the choice of drugs for prenatal treatment and determining the tactics of pregnancy management.