A biopsy system for retrieving biopsy tissue samples from different regions of the body is disclosed. The biopsy system includes a single use loading unit having a trocar assembly and a knife assembly. A trocar driver is operably connected to the trocar assembly and is actuable to move a trocar between retracted and advanced positions. The trocar driver is disengaged from the trocar assembly prior to firing the trocar into a target tissue mass to reduce drag on the trocar during firing. A knife driver is operably connected to the knife assembly such that when actuated, a knife is both rotatably and axially advanced about the trocar.