Dense two-dimensional periodic photonic bandgap structures are produced inpoly(methyl methacrylate) thin films using nanoimprint lithography (NIL). The stamporiginal was made by electron beam lithography. Then, a high versatility of theprocess was achieved by fabricating copies of the stamp original via NIL, whichenables varying and optimizing both fill factors and aspect ratios independently.For reliable stamp copying over the whole structural areas, the nanorheologicalbehaviour had to be considered. Using those stamp copies, polymeric photonic bandgap structures with an aspect ratio as high as 2 were successfully replicated.