TheFNmethod is used, in the field of rarefied gas dynamics, to develop a complete solution for the cylindrical Poiseuille flow and thermal creep problems. The linearized Bhatnagar–Gross–Krook (BGK) model and purely diffuse reflection at the surface are used to describe the physical problem. The derived set of singular integral equations is solved by polynomial expansion and collocation. By choosing suitableFNapproximations, the solution of both problems under consideration is accomplished with a single matrix inversion, minimizing computational time and effort. The converged numerical results for the flow rates and the velocity profiles are correct to four significant figures, thus supporting the results of previous authors achieved by other methods.