The introduction of synthetic food flavorings has been widely increased in Egypt. These materials are used in both industrial and household processing scale. Many of these materials, which commonly used in the household preparations, are anonymous. The use of not controlled food flavorings (unknown) might exposure the consumers health to various health risks. These unknown flavoring materials used in food processing were subjected to chemically and biologically evaluation. Heavy metals contents and FT-IR analysis were determined. A nutrition experiment on rats was conducted to determine growth parameters, liver and kidney functions. Also, histological examination on brain and testes was done. Results indicated that studied heavy metals content of flavoring agents did not exceed the permissible limits of each that stated by international organizations. FT-IR spectra indicated that the studied unknown flavoring agents contained many functional groups such as hydroxyl, vinyl, carbonyl, amide, alcohol and aliphatic amine groups. As for growth parameters, body weight of all studied groups significantly decreased via increasing dosages of synthetic flavoring agents  (10, 40, 70 and 100 mg/kg/day) compared with those of control group. Flavoring agents had a negative effect on liver and kidney functions where liver enzymes activity (ALT and AST), creatinine and urea concentrations of treated groups were significantly increased compared with those of control group. While, SOD activity and albumin content were significantly decreased. With increasing the administrated concentration of synthetic flavors the adverse effects of biological parameters had been significantly increased.As well as, brain histological sections proved to show congestion and edema. Testes showed irregular shape of seminiferous tubules, atrophy of leydig cells and disturbance in spermatogenesis. Results indicated that the used doses of the synthetic food flavorings were mostly attributable to hepatocellular damage, renal failure and decrease in spermatogenesis process. In conclusion, synthetic food flavorings had negatively affected the biological performance of Albino male rats. More studies could be required to re-evaluate the health effects of  used food flavors in the local markets. Government must take conclusive decisions and put restrictions to reduce these hazard components import, handling and using.