Pregnant women have an increased risk of having the usual arrhythmias seen in women of childbearing age. Most of these are benign sinus tachycardias or bradycardias or atrial and ventricular ectopic beats. Women who have had sustained supraventricular or ventricular tachycardias before pregnancy frequently develop them during pregnancy. These arrhythmias often have enough hemodynamic significance to decrease uterine blood flow, which adds a sense of urgency for treatment. The management is similar to that of nonpregnant women, with nuances important for the protection of the developing fetus.