The Einstein's field equations of Friedmann-Robertson-Walker universes filled with a dissipative fluid described by both the truncated and non-truncated causal transport equations are analyzed using techniques from dynamical systems theory. The equations of state, as well as the phase space, are different from those used in the recent literature. In the de Sitter expansion both the hydrodynamic approximation and the non-thermalizing condition can be fulfilled simultaneously. For Λ=0 these expansions turn out to be stable provided a certain parameter of the fluid is lower than 1/2. The more general case Λ>0 is studied in detail as well. © 1996 American Institute of Physics.