We present results on a lithographic approach that combines nanoimprint(NIL) and x-ray lithography (XRL) for fabricating unconventional three-dimensional (3D) polymer structures. The use of XRL for structuring a prepatterned resist by NIL gives rise to high-resolution high-aspect-ratio structures whose overall profile is enveloped by the original 3D imprinted profile. The technological potential of this method has been demonstrated by patterning several different types of structures with XRL on an hexagonal affay of hemispheres previously obtained by nanoimprinting. (C) 2004 American Vacuum Society.