Background: This phase III study was undertaken to evaluate the efficacy of an allogeneic whole-cell vaccine (Canvaxin™) plus bacillus Calmette-Guerin (BCG) after complete resection of stage IV melanoma. Methods: After complete resection of ≤5 distant metastases, patients were randomly assigned to BCG+Canvaxin (BCG/Cv) or BCG+placebo (BCG/Pl). The primary endpoint was overall survival (OS); secondary endpoints were disease-free survival (DFS), and immune response measured by skin test (ClinicalTrials.gov identifier: NCT00052156). Results: Beginning in May 1998, 496 patients were randomized. In April 2005, the Data Safety Monitoring Board recommended stopping enrollment due to a low probability of efficacy. At that time, median OS and 5-year OS rate were 38.6 months and 44.9%, respectively, for BCG/Pl versus 31.4 months and 39.6% in the BCG/Cv group (hazard ratio (HR), 1.18; p = 0.250). Follow-up was extended at several trial sites through March 2010. Median OS and 5-year and 10-year survival was 39.1 months, 43.3 and 33.3%, respectively, for BCG/Pl versus 34.9 months, 42.5 and 36.4%, in the BCG/Cv group (HR 1.053; p = 0.696). Median DFS, 5- and 10-year DFS were 7.6 months, 23.8 and 21.7%, respectively, for BCG/Pl versus 8.5 months, 30.0%, and 30.0%, respectively, for the BCG/Cv group (HR 0.882; p = 0.260). Positive DTH skin testing correlated with increased survival. Discussion: In this, the largest study of postsurgical adjuvant therapy for stage IV melanoma reported to date, BCG/Cv did not improve outcomes over BCG/placebo. Favorable long-term survival among study patients suggests that metastasectomy should be considered for selected patients with stage IV melanoma.