The effect of the Flex-Stent® on immediate and longterm angiographic and clinical results for acute and threatened closure was evaluated in 42 consecutive patients with coronary arterial segments <3.0 mm in diameter after percutoneous-transluminal coronary angioplasty (PTCA). Forty-two consecutive patients were treated with Flex-Scent (2.0 or 2.5 mm) for acute or threatened closure and 32 (76%) had threatened (24%) had acute closure and 32 (76%) had threatened closure with a residual luminal stenosis of >50%. Successful stetent deployment was achieved in 40 patients (95%) with a primary clinical success rate of 90% (freedom from myocardial infarction, coronary artery surgery, and death). In-hospital complications occurred in 5 patients (some patients fell into more than one category): 3 (7.1 %) had coronary bypass surgery, 1 (2.4%) had acute stent thrombosis, 1 (2.4%) had subacute stent thrombosis, 2 (4.8%) had myocardial infarction, and 1 (2.4%) had dextran allergy. There was no hospital death. Clinical follow-up was complete at a mean of 14.8 ± 7.6 months, and recurrence of angina was noted in 20 of 38 eligible patients (53%). Angiographic restenosis was found in 19, of 29 patients (66%) (76.3% of eligible patients) on follow-up angiography (mean 5.9 ± 4.6 months). Fourteen pa bents (74%) underwent successful repeat PTCA at the stented site, 4 of 38 patients (11%) had bypass surgery. Intracoronary stenting in the treatment of acute or threatened closure in arteries <3.0 mm is effective in improving the acute clinical outcome and is a viable nonsurgical alternative for this subset of patients.