Fatty aldehydes are an important group of fragrance and flavor compounds that are found in different fruits and flowers. A biotechnological synthesis of fatty aldehydes based on Escherichia coli cells expressing an alpha-dioxygenase (alpha DOX) from Oryza sativa (rice) is presented. alpha-Dioxygenases are the initial enzymes of alpha-oxidation in plants and oxidize long and medium-chain C (n) fatty acids to 2-hydroperoxy fatty acids. The latter are converted to C (n -aEuro parts per thousand 1) fatty aldehydes by spontaneous decarboxylation. Successful expression of alpha DOX in E. coli was proven by an in vitro luciferase assay. Using resting cells of this recombinant E. coli strain, conversion of different fatty acids to the respective fatty aldehydes shortened by one carbon atom was demonstrated. The usage of Triton X 100 improves the conversion rate up to 1 g aldehyde per liter per hour. Easy reuse of the cells was demonstrated by performing a second biotransformation without any loss of biocatalytic activity.