The present study investigated the genotoxic and cytotoxic effects of Sunset Yellow and Brilliant Blue. Genotoxic and cytotoxic activities of the food additives were evaluated in lymphocyte cell cultures using mitotic index, replication index and micronucleus assay. Mitotic index frequencies and replication index values were decreased and micronucleus frequency was increased with increasing concentrations of Sunset Yellow and Brilliant Blue. The changes in mitotic index and micronucleus are statistically significant [p<0.05] . The results show that the Sunset Yellow and Brilliant Blue can have cytotoxic and genotoxic potential. It care must be taken when using these materials as a food additive