Biological macromolecules are considerably denatured when processed for conventional electron microscopy. To test the applicability of scanning tunneling microscopy for these purposes we chose fibrous protein collagen I pipetted and dried on an oriented pyrolytic graphite surface. Survey scans made over 500×500 nm2showed separate and branching ridges of various lengths as well as regions of densely packed material. In scans over 50×50 nm2there were structures with regular protrusions propoused to be generated at a basic interval of 9 nm. The recorded images corresponded well with biochemically measured dimensions of type I collagen cyanogen bromide peptides.