The　present　study　was　to　determine　the　effectiveness　of　electron　beam　irradiation　for　degradation　of　the　antiepileptic　drug　primidone　(PMD)　in　aqueous　solution.　The　results　showed　that　PMD　degradation　followed　pseudo-first-order　kinetics.　The　dose　constant　determined　in　this　study　ranged　from　1.26　to　4.59　kGy(-1),　and　decreased　with　an　increase　in　the　PMD　initial　concentration,　whereas　the　initial　radiation　chemical　yield　for　the　loss　of　PMD　decreased　with　increasing　of　absorbed　dose　and　increased　as　the　PMD　concentration　increased.　The　effects　of　medium　pH,　the　presence　of　SO42-,　SO32-,　CO32-,　HCO3-,　NO3-　and　NO2-　anions,　H2O2,　iso-propanol,　and　saturated　solutions　of　N-2,　O-2,　N2O　were　also　investigated.　The　results　demonstrated　that　the　(OH)-O-center　dot　took　the　most　important　role　in　the　degradation　of　PMD,　while　the　reductive　e(aq)(-)　and　H-center　dot　took　the　less　important　role　in　PMD　degradation.　Major　degradation　products　of　PMD,　including　degradation　intermediates,　low　weight　organic　acids　and　some　inorganic　ions　were　detected　by　LC/MS/MS　and　IC.　Formic　acid,　acetic　acid,　oxalic　acid,　maleic　acid　and　NO3-,　NH4+　were　identified　in　the　irradiated　solutions.　Possible　pathways　for　PMD　decomposition　by　electron　beam　irradiation　in　aqueous　solution　were　proposed.　(C)　2015　Elsevier　B.V.　All　rights　reserved.