Food additives have been used by mankind for centuries. Most food additives are considered safe; however, some are known to be toxic or carcinogenic. Aldehydes occur as natural (flavoring) constituents in a wide variety of foods and food components. This review highlights the nephrotoxicity of the major flavoring agent - cinnamaldehyde. Cinnamaldehyde has been in public use since 1900. It is a yellowish liquid with a strong pleasant fragrance derived from the bark of Cinnamomum cultivated trees. Cinnamaldehyde also occurs in several brands of cinnamon breads, cereals, cookies, puddings, and fruit juices. Cinnamaldehyde is chemically related to toxicologically more active compounds, like acrolein and crotonaldehyde. Besides cinnamaldehyde, acute toxicity of other major components of Cinnamomum - cinnamic acid and cinnamyl alcohol were observed in rats. Thus, concern about the safety of cinnamaldehyde in general was raised. Many species of the genus Cinnamomum, the main source of cinnamaldehyde, are distributed in different regions of India. Cinnamaldehyde is widely found in many Indian foods and medicinal and cosmetic products. Thus, cinnamaldehyde has a high potential for human consumption in India. This research work on the toxic effects of cinnamaldehyde on kidney was conducted at the World Health Organization (WHO) suggested Acceptable Daily Intake (ADI) level (0.7 mg / kg body weight). Histopathological changes of kidney were accompanied by alterations in the antioxidant status, level of marker enzymes and other chemical constituents. Finally, it was concluded that cinnamaldehyde has a toxic effect on the rat kidney and its effect is time and dose dependent.