Stevia (Stevia rebaudiana Bertoni) extract has been recently introduced to Egypt as a non-nutritive sweetener. In this work we tested the possible capability of stevia extract in inducing micro as well as macro DNA lesions. The golden hamster (Mesocricetus auratus; 2n = 44); and human lymphocyte (Homo sapiens, 2n =46) genomes were employed to test the genotoxicity of the extract on a more sensitive genome as well as on the human genome directly. Various short-term genotoxic bioassays were used including analysis of chromosomal abnormalities in hamster bone marrow and human lymphocytes, in vivo induction of sister chromatid exchanges in hamster bone marrow, in vitro induction of sister chromatid exchanges in human lymphocyte culture, micronucleus test in hamster bone marrow.                 The study shows that the two genomes respond to the extract differently. The extract induces significant levels of chromosome abnormalities in hamster, whereas it does not induce such higher levels of abnormalities in human lymphocyte culture. Analysis of sister chromatid exchange frequencies revealed that the extract induces significant levels of primary DNA damage in hamster bone marrow compared to the human lymphocytes. This study concludes that hamster seems to be more sensitive compared to human and other experimental genetic models used in genotoxic assays. Data from this study and previous studies on other genetic models are discussed.