What is Testosterone Cypionate ? Testosterone cypionate (brand names Depo-Testosterone, many others), or testosterone cipionate, also known as testosterone cyclopentylpropionate or testosterone cyclopentanepropionate, is an androgen and anabolic steroid and a testosterone ester. Along with testosterone enanthate, testosterone propionate, and testosterone undecanoate, it is one of the most widely used testosterone esters. Testosterone Cypionate CAS No.: 58-20-8 Molecular Formula: C27H40O3 …