PURPOSE: To identify variables predictive of long-term patency after femoropopliteal angioplasty. MATERIALS AND METHODS: The primary patency of 219 limbs in 205 patients from a multicenter registry who underwent femoropopliteal angioplasty between January 1, 1992, and December 31, 1994, was prospectively monitored with a combination of angiography, noninvasive hemodynamic testing, and clinical outcome. Patient demographic, angiographic, and hemodynamic variables were examined alone and in combination to determine effect on long-term primary patency. Each limb was graded as Category 1-4 according to the American Heart Association (AHA) criteria for arterial lesions, and differences in outcome for each category were examined. Primary patency and intergroup analysis were determined with use of the Kaplan-Meier method and log-rank test, respectively. Cox proportional hazards models were used to calculate relative risks for predictive variables. RESULTS: Primary patency rates for all limbs (on an intent-to-treat basis) at 12, 24, and 36 months were 87% +/- 3%, 80% +/- 3%, and 69% +/- 5%, respectively. Primary patency at 48 and 60 months was 55% +/- 7%. Poor tibial runoff (single tibial vessel with 50%-99% stenosis or occlusion) was most predictive of occlusion (relative risk 8.5, P <.0001). The presence of diabetes or renal failure was associated with lower long-term patency (relative risk 5.5 and 4.0, P <.0001 and.0002, respectively). Long-term patency was higher with AHA Category 1 lesions (P =.006), and no significant difference in patency was observed between Category 2 and 3 lesions (P =.65). A multivariate Cox proportional hazards model showed only the stratified runoff score and the presence of diabetes to be significant determinants of long-term patency. CONCLUSION: Poor tibial runoff is most predictive of lower long-term patency rates. Diabetes is also independently associated with lower long-term patency rates. The criteria that distinguish Category 2 and 3 lesions do not predict differences in long-term patency, nor do they serve to identify lesions best treated with surgical bypass. This suggests that indications for femoral angioplasty can be extended to include longer and more complex Category 3 lesions.