Using the Fourier-Galerkin method with domain truncation strategy, Stokes' first problem for Oldroyd four-constant liquid on a semi-infinite interval is studied. It is shown that the Fourier-Galerkin approximations are convergent on the bounded interval. Moreover, an efficient and accurate algorithm based on the Fourier-Galerkin approximations is developed and implemented in solving the differential equations related to the present problem. Also, the effects of non-Newtonian parameters on the flow characteristics are obtained and analyzed. The method developed here is so general that it can be used to study the mathematical models that involve the flow of viscous fluids with shear rate-dependent properties: For example, models dealing with polymer processing, tribology & lubrication, and food processing. (C) 2007 Elsevier Ltd. All rights reserved.