BACKGROUND: Hand ischemia is a rare but potentially devastating complication of radial artery cannulation for arterial monitoring. The causes and ultimate outcomes of hand ischemia after radial artery cannulation are unclear. STUDY DESIGN: My colleagues and I reviewed the clinical course of radial cannula-induced arterial thrombosis in eight patients during a recent 5-year period. RESULTS: Mean (± SD) duration of radial artery ischemia was 3 ± 2 days. Injuries were associated with advanced (grade IIb) ischemia that affected the entire hand in four patients and first three digits in the other four patients. Radial artery thrombosis was documented using noninvasive tests or arteriography in all patients. Five injuries were initially treated with thrombectomy and patch angioplasty (n = 4) or vein graft interposition (n = 1); two others were treated nonoperatively with vasodilators, and one was observed without treatment. Three of the four patch angioplasty repairs occluded within 24 hours. Regardless of patency, all patients who survived arterial repairs had continuing ischemia that resulted in digital gangrene or amputation. In contrast, gangrene developed in only one patient treated nonoperatively. CONCLUSIONS: These data show that hand ischemia after radial artery cannulation is associated with high risk of tissue loss or amputation. Operative repair offered no advantage over nonoperative therapy in prevention of digital gangrene in this series. We hypothesize that digital gangrene results from distal embolization from the site of the initial arterial thrombosis, producing ischemia that is not remediated by radial artery revascularization. Nonoperative therapy with vasodilators can be equally effective in treating cannula-induced radial artery injuries in some patients.