8526 Background: Many randomised trials have evaluated the role of adjuvant interferon-a (IFN) in high-risk melanoma, some suggesting benefit and others not. To assess the totality of current evidence, an individual patient data (IPD) meta-analysis of all available trials was performed. Methods: Standard IPD meta-analysis methods were used to assess event-free (EFS) and overall survival (OS), with odds ratios (OR) and 95% confidence intervals (CI) calculated. Trials were divided by dose of IFN - high (20 MU/m2), intermediate (5–10 MU), low (3 MU) and very low (1 MU). Subgroup analyses by patient age, gender and disease characteristics were also performed. Results: IPD was provided for 10 of 13 reported trials of IFN vs. no IFN (for the other 3 trials published data were used). 6067 patients (IPD available for 85%) were included in the analysis, with over 3,700 and 3,000 events for EFS and OS. There was statistically significant benefit for IFN for both EFS (OR=0.87, CI=0.81–0.93, p=0.00006) and OS (0.9, 0...