Food colorants are used all over the world in great amount. However, their use in food is still controversial. It causes and will cause severe tension to the consumers as the sensitivity of people increases to general health. This work was carried out to study and compare between the possible toxic effect of some natural (tumeric, carmine and chlorophyll) and synthetic (fast green, annatto and sunset-yellow), food colorants on liver and kidney function of young male albino rats. Such effect might explain hyperactivity of children that was claimed associated with consumption of food colorants. The study revealed that administration of both natural and synthetic food colorants (permitted dose) significantly increases serum AST and serum urea. All colorants with the exception of sun-set yellow significantly increase serum total bilirubin. While, chlorophyll, fast-green and sun-set yellow were significantly increase serum ALT. Some of the colorants used have a retard destructive effect on some vital organ functions, which extends even after the recovery period. Therefore, large quantities and /or long periods of colorants administration should not be used as additive in man's diet or as a drink. Hence, these colorants should restrictly be used in nutritional therapy. And more caring must be done prevent our children to eat or drink these colorants with much amounts or for long period.