An assembly for taking a biopsy sample from a site within the body of a patient includes a housing that is positioned over the bedside table of a patient and contains a biopsy actuator assembly used to propel the needles. The biopsy actuator includes a base-frame receiving a cannula slide and a stylet slide, each slide containing a needle holder for propelling the needles with the aid of one spring each. An electrical magnet-triggering device is provided for releasing the stylet slide, which in turn is adapted during the final phase of its propulsion to release the cannula slide. The housing fits to a needle assembly including a flexible guide tube, a flexible cannula and a stylet. The assembly further includes an electrocautery element and a mechanism for adjusting the forward speed and the depth of invasion of the needles.