The objective of the work is the determination of the importance of transport effects in subcritical systems driven by an oscillated neutron source. The transport equation is solved in the frequency domain for two-dimensional source-driven systems, using the discrete ordinates method. Some problems connected with the application of synthetic acceleration procedures for the solution of the transport equation in the frequency domain are addressed. Comparisons between transport and diffusion results allow identification of physical situations (multiplying system geometry and material characteristics) in which transport effects could be important for a certain range of the frequency of the source.