Royal jelly (RJ) is one the most important bee product because it strongly influences the larval development in the hive, including the queen bee. In literature, RJ is known for its antioxidant, immunoregulatory, antifungal, antibiotical, erythropoietic, hypoglycemic, anticholesteremic, antithyroidic, anti-osteoporotic and estrogenic properties. However, it is surprising how rare the scientific evidence about RJ antineoplastic capacity are. That being said, we investigated, for the first time, the in vitro bioactivity of six different RJs on the growth of three different mammalian cell lines: immortalized murine myoblasts (C2C12), human prostate cancer (PC3) and human neuroblastoma (SH-SY5Y). These studies were performed treating the cells with the only lipophilic, or hydrophilic, fraction of the RJs, a scientific approach never performed before. Moreover, chemical and protein profiles of all RJs were finely characterized, in qualitative and quantitative terms, by GC-MS and 1D-SDS-PAGE, respectively, in order to give a complete framework to the research. Despite the deep differences we found in the composition of each sample, unexpectedly, RJs showed comparable or very similar biological effects. In particular, our attention was captured by the extraordinary antiproliferative activity of the lipophilic extract of all RJs against SH-SY5Y cells, suggesting a potential medical application of this bee product to prevent the onset and slow down the growth of human neuroblastoma.