We investigate analytically and numerically aerodynamic focusing of aerosol particles in the incompressible Poiseuille flow in a two-dimensional channel where the channel walls perform small oscillations perpendicular to the channel axis. The fluid-particle interaction is described by a linear drag force, Focusing efficiency is investigated for variety of flow and particle parameters, expressed in terms of dimensionless groups, namely parameter epsilon, characterizing the amplitude of wall oscillations; flow velocity parameter Pi(U) = U/omega h where U is the maximal velocity of the imposed flow, h is the channel half-height, omega is the angular frequency of oscillations; and frequency parameter omega tau, where tau is Stokes relaxation time. It is shown that wall channel oscillations with frequency of about 1 kHz can focus micron-size particles on axial distances comparable to several channel heights. (C) 2008 Elsevier Ltd. All rights reserved.