AMINO-ACIDS are often mentioned as synergisbic antioxidants. Their mechanism of enhancing the effect, of primary antioxidants can be explained in different ways: by chelation of pro-oxidative metal traces1 and by regeneration of oxidized primary antioxidants2-4. It has also been shown that amino-acids may play the part of synergistic antioxidants as natural constituents of food material5. On the other hand, there is a lack of systematic survey on a more general basis of this effect of amino-acids. Certain results have been published, which, however, refer to special conditions6,7. No data are available on the effect of amino-acids in absence of other anti-oxidative substances. © 1960 Nature Publishing Group.