OBJECTIVE: The ILVwas developed with specific aims:1) a minimally invasive procedure done thru a 4mm space, 2) no posterior dissection of the vas, 3) cautery closures without clips or ties. In addition, long standing practices were eliminated:1) removal of a vas section, 2) fascial interposition (FI), 3) complete transection of the vas. Herein,we report experience with 901 procedures developed in 3 Phases, with IRB approval. DESIGN: ILV development involved a systematic critique of existing vasectomy procedures espiecially those with all cautery closures. Several new innovations were introduced such as detubularizarion (DT) of a vas section, and use of ILV instruments for specific functions. MATERIALS AND METHODS: A mini-tenaculum grasped the upper 1/2 of the vas and its sheath thru a 4mm opening.The structures were elevated, and cut longitudinally for 5 mm with a fine scissors (DT). The opening permitted the cautery tip to enter and burn the mucosa of the abdominal lumen. A second mini tenaculum was placed on the abdominal side of the DT segment and the first clamp was removed. The cautery tip entered the testicular lumen to burn the mucosa. Then, the cautery tip was placed in line with the DT section to burn the remaining mucosa and anterior 1/2 of the side walls. The back wall of the vas was not transected, and the intact, cauterized vas was replaced into the scrotum. Two or more semen analyses were performed starting at 6 weeks. RESULTS: Failure persistence of any sperm in semen after 4 months. Phase 1(DT, transection & FI)- 675 procedures, 1 failure and 18 return visits for scrotal swelling. Phase 2 (ILV instruments, DT & no FI)-105, 1 failure, 5 returns. Phase 3 (No posterior dissection, no FI & no transection)- 121, 0 failures, 3 returns. CONCLUSIONS: Phase 3 ILVs include: DT of a 5mm section of vas, abdominal and testicular luminal cautery, mucosal and wall cautery of the DTsection, no posterior dissection, no back wall transection. With ILV instruments the procedure is rapid, reliable and has less post op swelling.