Abnormalities of impulse generation and propagation in the heart can lead to cardiac arrhythmias. In recent years, cardiac biological pacemakers created by genetically engineering of genes or cells have been successfully tested in several preclinical studies. Hyperpolarization-activated cyclic-nucleotide-modulated (HCN) channels (pacemaker channels) play a critical role in modulation of cardiac automaticity. HCN gene transfer of myocardium generates biological pacemaker in animals with experimental bradycardia. Implantation of various cells to myocardium has been investigated for cardiac repair of conduction damage in animal studies. This presentation reviews the research progress in the field of gene and cell therapies for cardiac arrhythmias and focuses on biological pacemaker and conduction repair.