Properties of a folded multipass unstable circular mirrors cavity designed for a gasdynamic laser have been studied by using a code developed for numerical modelling of a GDL performance. The results concerning the steady-state field patterns, gain and inversion population distributions along the GDL channel as well as values of the output power for different optical condigurations are discussed in the paper. The characteristics of the cavities considered are compared with those obtained for a two-oblong-cylindrical mirrors unstable resonator. Due to the high diffraction losses, incre-asing with the number of folding mirrors the output power of the beam obtained for the multipass cavity is considerably lower than that for the two-oblong mirrors resonator. Taking into account technological difficulties connected with manufacturing of oblong cylindrical mirrors appropriate for a large Fresnel number cavity, the multipass configuration seems to be more practicable.