Plant bioassays are quite sensitive and simple technique in comparison to animal bioassay to assess the genotoxicity and cytotoxicity of a chemical compound.  A. cepa and V .faba have been widely accepted for evaluation of genotoxicity and the assay is well known and commonly used in many laboratories in good correlation with results from other established test systems. .A. cepa has relatively large monocentric chromosomes and accepted as suitable test organism for the study of environmental mutagenesis.Also V. faba beans was used as indicator to determine genotoxic effect of synthetic dyes used as food additives. The mitotic index is one of the mitotic parameters, which reflects the genetic. control system of division and the existence of chromosomal aberrations in several organisms In the present work, the genotoxic effects of three food colorants on two types of living organisms i.e. (Allium cepa and Vicia faba) plants were studied. The three food colorants were (Ponceau 4R, Sunset yellow and Tartrazine). Each colorant was used in three concentrations 0.25%, 0.50% and 1.00%. The results showed that all  synthetic food  colorants which used in the experiment  decreased the mitotic indices in V.faba and A.cepa . Moreover the  synthetic food colors disturbed the percentages of mitotic stages and the chromosomes behavior  and configuration during the mitotic division.  Also, the study compared the effects occurring at molecular levels in Allium cepa and Vicia faba exposed to colored food at 1% concentration aqueous solution. The qualitative modifications arising in random amplified polymorphic DNA (RAPD) profiles as a measure of DNA effects were compared with control. Results showed that treatments of the above test samples reflect changes in RAPD profiles. Changes in RAPD patterns included variation in band intensity, loss of normal bands and appearance of new bands compared with control. More over the ability of different primer for producing DNA fragment is varied from genome to other. The results indicated that DNA polymorphism.