Low voltage-activated, T-type, calcium channels are thought to be involved in pacemaker activity, low threshold Ca2+ spikes, neuronal oscillations and resonance, and rebound burst firing. Mutations in T-type channel genes may be a contributing factor to neurological and cardiovascular disorders, such as epilepsy, arrhythmia, and hypertension. Due to the lack of selective blockers, little is known about their structure or molecular biology. This review discusses our recent findings on the cloning, chromosomal localization, and functional expression, of two novel channels, alpha1G and alpha1H. The biophysical properties of these cloned channels (distinctive voltage dependence, kinetics, and single channel conductance) demonstrates that these channels are members of the T-type Ca2+ channel family.