A method for operating a biopsy device for taking tissue samples includes coupling an electric power source to a tension slide via a removable biopsy needle unit, the removable biopsy needle unit including a biopsy needle and a cutting sheath coaxially arranged with the biopsy needle, the biopsy needle having a sample removal chamber rotating the cutting sheath via the electric power source to move the tension slide against an action of a spring locking the tension slide in a cocked position by a releasable locking mechanism and releasing the releasable locking mechanism when the tension slide is in the cocked position such that the tension slide is moved by the spring away from the cocked position to move the biopsy needle and the cutting sheath in a distal direction.
