This study evaluates the safety and efficacy of intracoronary stenting without anticoagulation, guided by intravascular ultrasound (IVUS). From March 1993 to January 1994, 359 patients with 452 lesions underwent Palmaz-Schatz stent implantation. After achieving an initial successful angiographic result with <20% stenosis, IVUS was performed to guide further balloon dilatation. Patients with adequate stent expansion confirmed by IVUS were treated only with antiplatelet therapy (ticlopidine for 1 month or aspirin). Clinical success (procedure success without early postprocedural events) at 2 months was achieved in 338 patients (94%). Optimal stent expansion was achieved in 321 patients (96%) with only antiplatelet therapy. Despite the absence of anticoagulation, there were only two acute stent thromboses (0.6%) and one subacute stent thrombosis (0.3%) at 2-month follow-up. At 6-month follow-up, angiographically documented stent occlusion occurred in 5 patients (1.6%). The overall event rate was relatively high due to intraprocedural complications in 16 patients (4.5%). However, when angiographically appropriate balloons were used for final stent dilations, intraprocedural complications decreased to 1%. The study concludes that the Palmaz-Schatz stent can be safely inserted in coronary arteries without subsequent anticoagulation, provided that stent expansion is adequate and there are no other flow-limiting lesions present. This technique significantly reduces hospital time and vascular complications and has a low stent thrombosis rate.This study evaluates the safety and efficacy of intracoronary stenting without anticoagulation, guided by intravascular ultrasound (IVUS). From March 1993 to January 1994, 359 patients with 452 lesions underwent Palmaz-Schatz stent implantation. After achieving an initial successful angiographic result with <20% stenosis, IVUS was performed to guide further balloon dilatation. Patients with adequate stent expansion confirmed by IVUS were treated only with antiplatelet therapy (ticlopidine for 1 month or aspirin). Clinical success (procedure success without early postprocedural events) at 2 months was achieved in 338 patients (94%). Optimal stent expansion was achieved in 321 patients (96%) with only antiplatelet therapy. Despite the absence of anticoagulation, there were only two acute stent thromboses (0.6%) and one subacute stent thrombosis (0.3%) at 2-month follow-up. At 6-month follow-up, angiographically documented stent occlusion occurred in 5 patients (1.6%). The overall event rate was relatively high due to intraprocedural complications in 16 patients (4.5%). However, when angiographically appropriate balloons were used for final stent dilations, intraprocedural complications decreased to 1%. The study concludes that the Palmaz-Schatz stent can be safely inserted in coronary arteries without subsequent anticoagulation, provided that stent expansion is adequate and there are no other flow-limiting lesions present. This technique significantly reduces hospital time and vascular complications and has a low stent thrombosis rate.