Prevalence of arrhythmias during pregnancy has been increasing and pre-existing arrhythmias have been getting worse. About 5% of arrhythmias arise de novo. The choice of the therapy is determined by clinical and prognostic severity of arrhythmia, by a type of it and the presence of structural heart disease. Non-pharmacological therapy, except of invasive radiation controlled procedures, is safe. The evidence that the chosen antiarrhythmic drug has no teratogenic effects and has low risk side effects for the mother and the fetus, is crucial. The basic principles of the treatment of arrhythmias during pregnancy are presented in the paper.