PURPOSE: To determine predictors of clot dissolution in patients undergoing catheter-directed urokinase thrombolysis for peripheral arterial occlusion (PAO). MATERIALS AND METHODS: The study included 103 patients with limb-threatening symptoms of embolism lasting 14 days or less and resulting from embolism (n = 20) or thrombosis (n = 83). Successful lysis was defined as restitution of antegrade flow with less than 20% diameter reduction by residual thrombus. Stepwise logistic regression was used to analyze the data. RESULTS: Relevant clinical variables were diabetic status (odds ratio, 0.75; P = .04 for diabetic patients), conduit type (1.25; P = .04 for native artery and 1.51; P = .02 for prosthetic graft), and number of arterial segments involved (1.60; P = .02 for one level and 1.42; P = .03 for two levels). Important procedural variables included intrathrombus positioning of catheter ports (odds ratio, 7.40; P = .001) and guide wire passage through the occlusion (3.10; P = .003). Absolute thrombus volume was nonpredictive but correlated with reperfusion time (P = .02) and infusion time (P = .01). CONCLUSION: Predictive parameters may help in the selection of candidates with PAO for thrombolytic therapy.