Histone　proteins　protect　cellular　DNA　from　radiationdamage.　Wefind　that　arginine,　a　major　component　of　histone　proteins,　protectsDNA　from　lesions　induced　by　low-energy　secondary　electrons　generatedby　radiation.　Thin　films　of　7　+/-　2,　12　+/-　4,　and　17　+/-　4　nm　thicknesses　containing　arginine-plasmid-DNA　complexesin　molar　ratio　of　[Arg(2+)]/[PO4　(-)]　=　16　are　irradiated　in　vacuum　with　5　and　10　eV　electrons.　Damageyields　are　measured　for　base　damages,　cross-links,　single-strand　breaks(SSBs),　double-strand　breaks,　and　other　clustered　lesions.　Most　damageresults　from　dissociative　electron　attachment.　Absolute　cross　sections(ACSs)　for　all　damage　types　are　extracted　from　yields　at　differentfilm　thicknesses.　Compared　with　bare　DNA,　these　ACSs　are　reduced　byfactors　of　up　to　4.4　in　Arg-DNA　complexes.　SSB　protection　isthe　highest.　Potentially　lethal　cluster　lesions　decrease　by　factorsof　up　to　2.2.　ACSs　are　critical　input　parameters　in　modeling　radiation-induceddamage　and　assessing　protection　factors　under　simulated　cellular　conditions.