Updated project metadata. Retinoblastoma (RB) is the most common tumor of the eye in early childhood. Despite recent advances in conservative treatment have greatly improved the visual outcome, local tumor control remain difficult in presence of massive vitreous seeding. Traditional biopsy has long been considered unsafe in RB, due to the risk of extraocular spread. Thus, the identification of new biomarkers is crucial to design safer diagnostic and more effective therapeutic approaches. Exosomes represent an interesting alternative to detect tumor-associated biomarkers. In this study we defined the protein signature of exosomes released by RB tumors (RBT) and vitreous seeding (RBVS) primary cell lines by high resolution mass spectrometry. A total of 5666 proteins were identified. Among these, 5223 and 3637 were expressed in exosome RBT and one RBVS group respectively.