It has recently been recognized that spatially inhomogeneous cloud and rain attenuation can substantially affect the precision of height measurements by a space-borne radar altimeter system (Walsh et al., 1984). Through computer simulation, it was found that typical levels of cloud and rain attenuation and associated spatial variabilities may degrade altimeter precision at 13.5 GHz and may cause severe degradation at 35 GHz. This degradation in precision is a result of radar signature distortion induced by variable attenuation over the beam-limited altimeter footprint. Because attenuation effects increase with frequency, range imprecision caused by them will significantly impact on the frequency selection of future space-borne altimeter systems. In this paper, altimeter precision degradtionn from highly idealized cloud and rain models is reviewed and extended to include degradiation resulting from the rain attenuation structure as measured by a ground-based radar system.