The authors investigate the simultaneous influence of thermomechanical and momentum exchange noise on the linear dynamic range DR of nanoresonators with random rough surfaces. The latter are characterized by the roughness amplitude w, the lateral correlation length xi, and the roughness exponent 0 <H <1. The dynamic range increases with increasing roughness (decreasing H and/or increasing roughness ratio w/xi) if the quality factor due to gas collisions is smaller than the intrinsic quality factor associated with thermomechanical noise. The influence of the roughness ratio w/xi on DR is significant for intermediate roughness exponents that are commonly observed in experiments. (C) 2007 American Institute of Physics.