First-principles　calculations　are　performed　to　study　the　modulation　of　energy　gaps　in　nitrogen　delta-doping　(N　delta-doping)　graphene　and　armchair-edge　graphene　nanoribbons　(AGNRs).　The　energy　gap　of　graphene　only　opens　at　a　large　nitrogen　doping　content.　For　AGNRs,　the　energy　gaps　tend　to　decrease　with　the　N　delta-doping,　and　an　interesting　transition　from　direct　to　indirect　bandgap　is　observed.　Moreover,　the　effects　of　N　delta-doping　on　energy　gaps　incline　to　decease　with　the　reduction　of　the　doping　content.　Our　results　may　help　to　design　novel　graphene-based　nanoelectronics　devices　by　controlling　N　delta-doping　of　graphene.　(C)　2011　American　Institute　of　Physics.　[doi:10.1063/1.3609243]