This paper details experimental and numerical studies of the effect of astigmatism on the performance of an unstable ring resonator with eight mirrors, causing a round trip 180 deg beam rotation, or seven mirrors, producing a beam flip. The resonators were studied with integer and integer plus one half equivalent Fresnel numbers and with and without intracavity spatial filtering. The experiment was performed on a CW electric discharge, fast flow CO2 unstable ring resonator with two removable and orthogonal focal line apertures (FLAs). The astigmatism was produced by rotating one cylindrical focusing mirror with respect to the other, producing astigmatism oriented at 45 deg to the focal line axes. Intracavity power, near field intensity distribution, and far field power and beam quality measurements were taken. The far field beam quality behavior with astigmatism was not very sensitive to the Fresnel number, but was dramatically dependent on the number of mirrors.