Biebrza National Park (BNP) in NE Poland is one of the least polluted regions of Europe and as such seems to be well suited for the determination of the composition of natural-background pollution of atmospheric dust. Samples of fallen dust were collected at monthly intervals between April 2003 and March 2004 in the isolated settlement of Grzędy. X-ray powder diffraction, scanning electron microscope images, and energy dispersive spectrometry revealed quartz, feldspars, micas, kaolinite, chlorite and hematite as major dust constituents. In addition, a few grains of Ni, Ni-Fe phosphide, and Fe-Ni-Cr oxides (probably of extraterrestrial origin) were observed. Anthropogenic constituents include amorphous aluminosilicates, barite, gypsum, Sn, Fe, Ti and Bi-W oxides. Quartz and feldspars constitute the majority of natural-dust pollution in BNP. Both grain size and mineral composition exhibit seasonal variations.