This paper summarizes (1) advances in our knowledge of coronal structures inferred from radio propagation measurements, and (2) gains in our understanding of the relationship between radio propagation and white-light coronagraph measurements. Radio propagation measurements confirm that streamers are ray-like structures as depicted in coronagraph pictures, but also reveal a hierarchy of filamentary structures throughout the corona, extending from the size of streamers down to scale sizes as small as about 1 km at the Sun(10−3 arcsec).Doppler scintillation measurements, therefore, open a new window on small-scale structure that has long eluded coronagraph measurements. In addition, high precision ranging measurements make it possible to investigate large-scale structures not yet observed in coronagraphs, such as plumes in equatorial coronal hole regions. ©1996 American Institute of Physics.