The purpose of this study was to assess the long-term effects of octreotide therapy on in-stent restenosis at 6-month follow-up coronary angiography and the clinical events after stenting. A randomized, double-blind, placebo-controlled trial was conducted to assess the effects of octreotide on restenosis after stenting. The patients ( n = 148) received either subcutaneous octreotide or placebo 1 h before the stenting procedure and then every 8 h for 3 weeks. Percent diameter stenosis was interpreted before and after stenting, and on a 6-month follow-up coronary angiogram by quantitative coronary angiography. The mean percent diameter stenosis of the octreotide group was significantly lower than that of the placebo group on the 6-month follow-up coronary angiograms (18.8% +/- 14.2% vs 35.0% +/- 19.2%, respectively; P = 0.001). The restenosis rate of the octreotide group was statistically lower than that of the placebo group (11.8% vs 26.4%, respectively; P << 0.05). With regard to major cardiovascular events, there was no significant difference between the octreotide and placebo groups. The administration of octreotide for treatment of in-stent restenosis results in a relatively low long-term angiographic restenosis rate and no significant acute effects on cardiovascular clinical events.