Impulse　radio　ultra-wideband　(IR-UWB)　receivers　based　on　kurtosis　detector　(KD)　can　achieve　much　better　performance　than　those　based　on　energy　detection　(ED).　However,　when　narrowband　interferences　(NBIs)　are　present,　the　KD-based　receivers　suffer　serious　performance　degradation.　In　this　paper,　a　modified　KD　(MKD)　is　proposed　to　improve　the　NBI　mitigation　ability　of　the　UWB　receiver.　Computer　simulation　results　show　that　although　the　bit-error-rate　(BER)　performances　of　the　MKD-based　receiver　are　marginally　lower　than　those　of　the　KD-based　receiver　when　no　NBI　is　present,　the　MKD-based　receiver　can　achieve　much　better　BER　performance　when　NBIs　are　present.　©　2013　IEEE.