3-Monochloropropane-1,2-diol (3-MCPD), also named 3-chloro-propanediol or α-chlorohydrin has long been known as a contaminant in certain heat-processed foods, including cereal products, coffee, fish, meat products, dairy products, and sauces on the basis of acid hydrolyzed vegetable protein 1. There is convincing evidence that fatty acid esters of 3-MCPD are also widespread in processed foods and that concentrations of these compounds exceed those of the corresponding chloropropanols. Whereas toxicology and biological effects of 3-MCPD have been studied quite thoroughly, very little is known about 3-MCPD esters of fatty acids. Recently, it has been reported that also esters of glycidol are formed during the refining of vegetable oils. There are no toxicological data available yet on glycidol esters but glycidol itself as an industrial chemical has been investigated and is known as genotoxic carcinogen found to induce tumors in different tissues after oral application. The following summary provides a condensed overview about gaps in knowledge concerning 3-MCPD esters and glycidol esters and addresses questions concerning toxicological relevance.