T-type Ca²⁺ channels have gained, 15 years after cloning, an immense interest as novel players in very unexpected cell functions, and its many relations to diseases have been discovered. This special issue provides a state-of-the-art overview on novel functional properties of T-type Ca²⁺ channels, unexpected cellular functions, and most importantly will also summarizes and review the involvement of this “tiny, transient” type of Ca²⁺ channels in several diseases. It is tried to bridge the gap between molecular biophysical properties of T-type Ca²⁺ channels and diseases providing finally a translational view on this amazing ion channel.