AbstractBypassing the anti‐tumor functions of the immune system is one of the keys to tumor survival. Tumors, especially hematological tumors, produce or express factors that retune T and B cells to inhibit the immune response. Coreceptors CD28 and CTLA‐4, and their ligands, CD80 and CD86, are involved in the immunological synapse and play an important role in immune processes. CD86 is widely expressed in hematological tumors, mainly of B‐cell origin, and only a few studies are available about its role in the pathogenesis. This study discusses the importance of CD86 expression in hematological malignancies. Does its presence help or hinder the development and survival of tumor cells? The answer to this question will facilitate a more profound comprehension of the biology of hematological malignancies and the development of new therapeutic options.