Background: Venous ulcers can be difficult to heal, and prognostic factors for healing have not been fully elucidated. Objective: The objective of this study was to analyze the results of a large multicenter venous ulcer trial to retrospectively establish prognostic factors for venous ulcer healing. Methods: This study examined data from a previously published prospective randomized placebo-controlled trial of an oral medication versus placebo treatment for venous ulcers. Local leg ulcer care involved the use of a moisture-retentive dressing and sustained graduated compression with a paste bandage and a self-adherent wrap. The oral medication or placebo was administered on a daily basis with the same dressings and bandage system in both groups for 12 weeks. A total of 165 patients completed the full 12-week treatment period; 83 received ifetroban, 82 received placebo. Results: There was no statistically significant difference in outcome between the two groups. The study showed that consistent local ulcer treatment with a clearly defined system of care was associated with an unexpectedly high percentage (55%) of long-standing large venous ulcers (mean duration, 27 months; mean area, 15.9 cm²) being healed in both groups. Baseline ulcer area and duration of leg ulcer were found to be important in predicting outcome. Ulcers of short duration were found to be most likely to heal. Percent healing and ulcer area at week 3 were good predictors of 100% healing. Ulcers that had at least 40% healing by week 3 predicted more than 70% of the outcomes correctly. Conclusion: From this large study it was determined that baseline ulcer area and ulcer duration are significant predictors of 100% healing and time to heal. Percent healing and ulcer area at week 3 are good predictors of complete ulcer healing. Ulcers that are large, long-standing, and slow to heal after 3 weeks of optimal therapy are unlikely to heal rapidly, and might benefit from alternative therapies. (J Am Acad Dermatol 2000;43:627-30.)