The effect of royal jelly (RJ) on the seed germination, seedling growth (radicle length, radicle number and fresh weight), mitotic activity and chromosomal aberrations of Allium cepa L. germinated under both normal conditions and salt stress were investigated in this work. The radicle length and fresh weight of the seeds germinated in the medium with RJ alone increased in comparison with ones of the control seeds germinated in distilled water medium while their germination percentage and radicle number statistically exhibited the same values as the control seeds. Furthermore, the mitotic index and frequency of chromosomal aberrations in root tip meristems of A. cepa seeds germinated in the medium with RJ alone demonstrated a significant increase according to ones of the control seeds germinated in distilled water medium. On the other hand, salt stress considerably inhibited the seed germination and seedling growth of A. cepa. In addition, it markedly decreased the mitotic index in root tip meristems of the seeds and increased the number of chromosomal aberrations. The inhibitive effect of salt on the seed germination, seedling growth and mitotic activity was alleviated in dramatically varying degrees by RJ application. However, the detrimental effects of salt on the chromosomal aberrations greatly increased with this treatment.