Incomplete revascularization is a common occurrence following angioplasty (PTCA) in patients with multivessel disease. To determine the short-term and long-term consequences of incomplete revascularization and the influence of the functional nature of the incomplete revascularization, 139 consecutive patients with multivessel disease were analyzed: 72 were completely revascularized and 67 had incomplete revascularization. The former patients had a lower incidence of prior myocardial infarction (MI) and prior bypass surgery (CABG). All patients had at least one lesion successfully dilated. In-hospital complications were insignificantly greater in incompletely revascularized patients compared with completely vascularized patients (mortality 3% versus 1%, MI 11% versus 4%, and emergency surgery 5% versus 0%). After 1 year of follow-up, incompletely revascularized patients had similar outcomes (mortality 6% versus 3%, MI 13% versus 7%, CABG 18% versus 15%, and repeat PTCA 19% versus 31%). The degree of incomplete revascularization was categorized as functionally adequate if all stenoses in bypassable vessels supporting viable myocardium were successfully dilated. Significantly fewer adverse events (death, MI, or CABG) occurred in the functionally adequate group than in the functionally inadequate group (27% versus 6%, p less than 0.04). This study demonstrates that incompletely revascularized patients have a favorable 1-year outcome and that patients with incomplete but functionally adequate revascularization have long-term results comparable with those of patients with complete revascularization. This study emphasizes the need to assess the functional significance of a stenosis when considering incomplete revascularization in a patient with multivessel disease.