Melatonin is a substance with antioxidant ability which occurs in the human body and in plants.The substance, that is important for the synthesis of melatonin, is tryptophan, which is synthe-sized to serotonin. The amount of serotonin coordinates the amount of melatonin.Its also named the ?sleepy hormone?, because the synthesis is regulated through the light and dark-signals in the retina. In the night, the synthesis of melatonin starts, and in the morning the degradation occurs. It can be synthesized too into the intestinal tract.For the analysis, several extraction methods, for getting higher concentrations of the substance, were used. Because of the low levels of melatonin in foods, it was necessary to work with a cation exchanger method. Furthermore, the extraction methods with diol- and C18-columns were used. The detection of the substances was realized with HPLC.The extraction methods with diol- and C18-columns were analyzed with thin-layer-chromatography. For the detection of the substance, we used, a UV-detector at 264 nm.Because of the low concentrations, the detection of the samples which were measured with the HPLC, were detected with a fluorescence detector at ?ex = 285 nm, ?em = 345 nm.The analyzed samples were mainly plant seeds, because of the ability of melatonin being an antioxidant, the concentrations were very high. The reason why they have such great amounts of melatonin could be, that they have to protect the genome of the seeds.Brown and white mustard-seeds as well as tomato- and grape seeds, anise, caraway and pota-toes were analyzed.In addition, raw and cooked wild rice was analyzed for melatonin. The results showed that the preparation of foods, especially the temperature, has an influence on the amount of melatonin.In the evening and at night milked milk was analyzed too for the amount of melatonin.