Objective: The in situ vein (ISV) bypass is uniquely suited to technical modifications designed to reduce the wound morbidity of infrainguinal revascularization. A technique of "blind" valvulotamy and selective vein branch ligation was used, and a preliminary study was performed to assess safety and efficacy. Methods: From November 1998 to July 2001, all patients for infrainguinal bypass procedures underwent evaluation for inclusion in the study. Thirty-five patients underwent ISV bypass procedures with an expandable, selfcentering valvulotome (ESV). Intraoperative selection of veins suitable for the study was assisted with venography and duplex scanning. The ISV bypass procedures were performed with initial groin and distal incisions, with smaller incisions to ligate significant arteriovenous fistulae (AVF). Duplex graft scanning was performed at routine intervals after surgery. Results: Thirty-seven ISV grafts were performed from the common femoral artery to the popliteal (n = 14), tibial (n = 20), and dorsalis pedis (n = 3) arteries. In 35 cases (95%), a full-length incision was avoided. With ESV, all valves in 34 cases (92%) were effectively lysed. Proximal extension of the distal incision was performed in four cases (10.8%). The mean number of incisions per case was 3.1 ± 1.7. One graft failed within 30 days (2.7%), with successful revision. During the early follow-up period (9.9 ± 7.3 months; range, 1 to 33 months), 44% of residual AVF closed spontaneously (15 of 34 AVF; 16 patients) and two anastomotic stenoses and two symptomatic AVF were corrected surgically. Four late graft occlusions occurred, with a 1-year cumulative primary patency rate of 77% and a secondary patency rate of 92%. Conclusion: Blind valvulotomy with ESV facilitates safe and effective minimally invasive ISV bypass. Resultant graft patency rates appear comparable with results with open techniques. This preliminary experience warrants further study to refine patient selection criteria and operative technique and to better clarify the natural history of residual AVF.