AbstractThere is a growing interest in the non‐erythropoietic, tissue‐protective and restorative actions of erythropoietin (EPO). While studies in this field have indicated that EPO can ameliorate chemotherapy‐induced peripheral neuropathy and cardiotoxicity, the issue whether EPO can positively or negatively affect cancer patients is a hot one. In this debate, many activities of EPO are being considered, including tissue/neuroprotection, angiogenesis, anti‐inflammatory activity, growth promotion, and inhibition of apoptosis. However, few studies have explored the interactions of EPO with the immune system. A study in this issue of the European Journal of Immunology by Katz et al. adds one new piece to the puzzle by showing that EPO can stimulate B cell‐mediated immunity.See accompanying article: http://dx.doi.org/10.1002/eji.200637025