Abstract: A renal tissue puncture site dilator with grooves in the jaws to receive a wire guide. The renal tissue dilator is a scissor-like surgical instrument, similar to a clamp, with jaws that have a triangular cross section to aid in tearing of tissue. The grooves in the jaws form a channel beginning at the tips of the jaws and exiting the jaws through the side of the jaws. This channel has a circular cross section, designed to slidably receive a wire guide. A needle is inserted into the renal tissue and a wire guide is threaded into the needle. The needle is removed. The instrument is threaded onto the wire guide and moved into the puncture site. The puncture site is dilated by opening the jaws of the clamp thereby tearing the renal tissue. The dilated tissue may be further dilated by rotating the clamp approximately 90.degree. and again opening the jaws of the clamp to tear the renal tissue further.