a biological tissue slicer having improvements therein which enable an inexperienced operator to rapidly prepare minimally traumatized tissue slices of excellent viability and of very uniform shape and dimension . the improvements limit contact of the cutting edge of the blade with the tissue to avoid irregular surfaces and trauma to the tissue sample . the device utilizes two pins and one or more magnets to hold the blade to a rapidly reciprocally moving blade holder such that uniform tissue slices of defined dimensions are produced by eliminating excessive lateral and vertical movement of the blade .