This study aimed to assess the allelopathic effect of aqueous leaf extract of Eucalyptus species on germination and radicle growth of Allium cepa and Vicia faba using different concentrations and times. Eucalyptus camaldulensis family Myrtaceae is one of the potential allelopathic plants having a number of allelochemicals and its essential oils possess pesticidal activity, these allelopathic agents are harmful to other plant species. Allium cepa and Vicia faba are very suitable for genotoxic studies and give fast and sensitive assay to detect environmental genotoxins and mutagens. Several concentrations of leaf extract of Eucalyptus camaldulensis (10-150%) were applied for 6, 12 and 18 h on seed germination and radicle growth of both tested plants. Moreover, we achieved a genotoxicity study at cytological level in root meristems of both plants by means of traditional cytogenetic approach, to evidence possible alterations in mitotic activity, chromosomal aberrations and micronuclei release. The results of this study showed that the leaf extract of E. camaldulensis had effects on germination and radicle growth of Allium cepa and Vicia faba and inhibition increased with increasing concentration. It was well documented that, release of allelochemicals occurs at the time of germination or at the early developmental stage. The aqueous leaf extract of Eucalyptus camaldulensis showed individually induced different mitotic changes in root tip cells of Allium cepa and Vicia faba. Such changes vary from (i) reduction of mitotic index of meristemtic cells, (ii) changes in phase index and (iii) production of a large number of chromosomal aberrations. Different types of mitotic abnormalities were observed in Allium cepa and Vicia faba in root tip cells in in both tested plants. These types were: irregular prophase, vacuolated nucleus at prophase, stickiness at different phases, disturbed metaphase, C-metaphase, bridges, forward chromosome, diagonal, multipolar, unequal sized nucleus at late telophase, micronucleus at interphase. The frequency of each type was variable.